the wheel and the hub

After seven years

2011-12-27T21:22:00.006+01:00

In the spirit of the previous post, some oldies goodies of the first year of this blog.

Subject Identity (2004-08-17) on difficulty of subject identification. The reference thread on topic map list is one year older. Just replace "topic map" by "triple store" or "RDF graph", and "topics" by "resources", and see that this critical question is still largely open.
The core requirement for semantic interoperability of [topic map] applications is interagreement on subject identification mechanisms, enabling both humans and applications to establish when and how different topics, either from the same topic map or different ones, should be interpreted as representing the same subject and processed accordingly.
Identification as an experimental protocol (2004-08-29) ... have we made any progress on this topic? Meanwile astronomers still prepare the GAIA mission, due to lift off in 2013.
Wikipedia URLs as Subject codes (2005-02-03) ... Jack Park anticipation, two years before DBpedia first release.
Wikipedia appears popular enough that its URLs might serve at least one important aspect of the subject identity issue ...

Indeed, more than the volatile and questionable content of DBpedia descriptions, it's the permanence and reliability of DBpedia URIs as subject indicators which makes them a core component of the Semantic Web.

A Web of unfinished weavings

2011-12-27T19:32:00.007+01:00

The Web is full of enthusiastic beginnings. Regular and steady follow-up, such as Astronomy Picture of The Day, of which daily archives are available since 1995, are harder to find. The statistics of this blog, and many more of the same, provide typical examples, but unfinished weaving is unfortunately not limited to personal looms, it's also undermining greater collective endeavors.

I was looking today at the state of some Wikipedia articles I'd been seriously contributing to, five years ago, such as the one about SKOS, and figured they need to be seriously updated. But if it's a lot of fun starting a new article, it's quite a boring task to go through it five years after, cleaning and updating it. And since it's a collaborative task, someone else could care after all. Many interpretations have been given to the fact that many people have given up editing Wikipedia, such as growing complexity, bureaucracy, edit wars etc. But people can cope with all this, as long as there is fun, and as long as there is something new every day. Wikipedia is now more than ten years old. It started in the previous century. At Web time scale, it's a very old-fashioned thing.

I see a similar trend undermining the Semantic Web. One could think that vocabularies used by linked data, since more and more people and application rely upon them, would be maintained and curated like precious assets. Actually after a year or so of exploration of this ecosystem, trying to federate the community around its crucial importance, I'm surprised that many of those vocabularies just sit there on a Web shelf, letting to everyone's guess if they're here to stay, if they have been or will be updated, if their publishers have any roadmap for their future evolution, or even if they still remember them.
Weaving the Web? If the weavers seem to be attracted every day by the next trendy loom, and forget to finish what's up on the old ones, the tapestry will always look like an unfinished patchwork. Is this the knowledge we want to build?

Making Sense of Ambiguity

2010-11-05T08:50:00.002+01:00

Resource Identity and Semantic Extensions: Making Sense of Ambiguity
Paper presented by David Booth at Semantic Technology Conference in San Francisco, 25 June 2010. Just do read it and try to make sense of it. The best analysis of the issue I've read so far.

Coreference using substitution rules

2010-07-13T17:01:00.006+02:00

Note : This is mostly copied/adapted from a message I posted last week in yet another conversation about the identity issue on W3C Library Linked Data Incubator Group internal mailing list.

Basically, most proposals to tackle the identity issue have boiled down so far to use direct assertions. To express that http://ex1.org/foo and http://ex2.org/bar denote more or less exactly the same thing, one uses dedicated predicates to make declarations such as:

http://ex1.org/foo p http://ex2.org/bar

The predicate p may stand here for owl:sameAs, rdfs:seeAlso; skos:exactMatch; umbel:isLike, any future foaf:whatever ... all those predicates conveying some kind of co-reference. In fact, even if it's not respected, among those only owl:sameAs has hard-defined semantics, the other ones can be interpreted at will by applications, through any follow-your-nose heuristics. Moreover, defining formal semantics for any of those will not prevent hacking. You can define as many same-ness similarity properties you like, they are bound to be used and abused the same way owl:sameAs has been. And if you consider that owl:sameAs semantics are as straightforward as can be, go figure how more subtle definitions will be hacked.

But there are other ways to explore this issue, including the radical "blank hub" way introduced here years ago. The path I would like to explore now uses operational rules rather than declarative assertions, and in particular substitution rules.

The basic principle is as following : Two denotations (e.g., URIs) are (somehow) co-referent if they can be substituted to each other in (some, many, most, all) assertions.

An owl:sameAs declaration amounts to absolute substitutability. When substitutability is partial, substitution rules could assert the conditions under which substitution is valid.

For exemple one could say that ex:author is substitutable to dc:creator if the subject of the predicate is a Book. Put formally, using e.g., RIF Basic Logic Dialect

Forall ?x ?p (ex:author(?x ?p) :- And(?x#ex:Book dc:creator(?x ?p))

This rule is different, and in fact independent of a declaration such as

ex:author rdfs:subPropertyOf dc:creator

because it does not say anything about the use of those properties outside the Book class.

Let's take an example discussed at length a few months ago on DBpedia forum.

ex1:MichelleObama rdf:type foaf:Person
ex2:MichelleObama rdf:type skos:Concept

In which context are those URIs substitutable? Certainly not for assertions using either predicates specific to the class foaf:Person (foaf:mbox) or specific to the class skos:Concept (skos:related) or which would bear different values for the two resources (dcterms:date). But they are substitutable for example for labeling predicates, such as :

?x rdfs:label 'Michelle LaVaughn Robinson'

which hold for both URIs.

This could be captured by the following rule (using RIF syntax again)

Forall ?name (rdfs:label(ex2:MichelleObama ?name) :- rdfs:label(ex1:MichelleObama ?name))

Using such rules has several advantages over declarative assertions:

- They do not need extra vocabulary to be defined and (mis)understood
- They have non-ambiguous formal interpretation
- They are flexible ad libitum to cover the whole spectrum of similarity-sameness flavours.

They can be expressed in various, more or less expressive rule languages, such as SPARQL CONSTRUCT.

What 'mean' means

2010-07-01T15:23:00.006+02:00

Twitter drives you lazy at least, and sometimes overly cryptic. It really happens that you can't really encapsulate what you have to say in 140 characters. So I feel necessary to expand here a bit on a recent tweet.
I've been working for a couple of months now with Gerard de Melo at Lexvo.org. The first objective was to make an example of Linked Data both social and technical good practice. If you have published a set of URIs, and find out afterwards that another set for the same resources has better quality, and moreover you have not the bandwidth or resources to maintain your dataset, what should you do? The example at hand was to redirect the work I've been doing at lingvoj.org towards the data at Lexvo.org which are far more complete, and moreover integrated in a general approach which I found extremely interesting.
The neat result of this work so far is that URIs for languages at lingvoj.org are now redirecting seamlessly to matching lexvo.org URIs, see e.g., http://www.lingvoj.org/lang/fr.
En passant I had fruitful exchanges with Gerard and brought little contributions, linking Lexvo.org resources to a couple of published vocabularies, such as LCSH and RAMEAU and other miscellaneous suggestions, acknowledged on the freshly updated Lexvo.org home page.

This new update, and the announcement Gerard will certainly push to the Semantic Web community in the next hours or days, is just on-time. Lexvo.org semiotic approach on lexical resources is a nice workaround to the RDF issue of 'literals as subjects' a topic which is again putting fire to the semantic Web mailing list. Lexvo.org FAQ explain very neatly why and how to coin URIs for terms in a specific language. So if the use of the RDF literal 'mean'@en as subject in RDF triples seems indeed problematic, the URI http://lexvo.org/id/term/eng/mean identifies this literal (a sign) in a non-ambiguous way, and allows it to be used as either subject or object of a triple in any current and hopefully any future form of RDF, without any technical or philosophical question.

I would like to stress a couple of very nice features allowed by the semiotic approach of Lexvo.org.

First you don't need to know if a term has already been described in the Lexvo.org data base to coin a URI for it. Try http://lexvo.org/id/term/eng/twidget (or for that matter any term that comes out of your hat). The URI will serve you at least the semantics you have implicitly embedded in its structure. This URI represents the term in english language of which literal form is 'twidget'. If there is no other assertions, it's because Lexvo.org data base is not aware of any other meaning of this term, nor translation in any other language.
This is more clever as it might seem at first sight. It means you can identify blindly in your own data any term you use by a lexvo.org URI. Maybe the service provides extra information on the term, maybe not. Maybe not today, but tomorrow if you ping lexvo.org saying "hey, add those URIs descriptions to your data base please".

The ambiguity of homographs is exposed but not resolved in the context of a language. http://lexvo.org/id/term/eng/mean provides the various meanings of the term in english (both verb and adjective). But cross-lingual homographs are distinct resources, such as http://lexvo.org/id/term/eng/coin and http://lexvo.org/id/term/fra/coin.

In a nutshell, Lexvo.org is an outstanding data set and service which deserves better visibility and widespread use in the Linked Data Cloud, providing a lexical and semiotic glue bearing a potentially enormous added value. A lot can be built on top of this. Whether or not literals as subjects eventually win their first-class RDF citizenship.

Looking for the stranger next door

2010-06-17T11:26:00.005+02:00

Back in 2002 I was involved in the building of a knowledge model for drug discovery, intended to be used by a knowledge portal of a major pharmaceutical group. Not sure it ever was implemented, but the work was great food for thought. Asking a leading scientist there what were his main functional requirements for a knowledge portal, I was stunned by the obvious simplicity of his answer. In short :

I want the system to stop pushing to me things I already know, such as my own publications, or those of my students and colleagues. What is of interest to me lies just behind this, one click away over the edge of my current knowledge. What I want to be pushed to me by the system should be different enough to question my current knowledge and make it move forward, but close enough to be easily connected to it.

I've met this requirement over and over since, made more or less explicit by all kinds of users. In a nutshell the interesting knowledge is both close to mine and different. It's the stranger living next door. But actually I've not seen yet any application meeting this requirement.
Indeed many applications push stuff based on user profile, social recommendations etc. But most of the time what they push to the user is something (or someone, in the case of social network recommendations) possibly unknown, but close and similar. The basic mechanism is Amazon's "if you like this, you should probably like that", or LinkedIn's "meet a friend of your friends". Very often the recommended stuff or person is not that unknown, and when it is, most of the time it's just adding a layer to your current knowledge or social cocoon. To find out something or someone both new and challenging, the best way is still to-date random browsing and serendipity. That's basically how I found out about PDF 2010 conference, through an excellent report by Marcia Stepanek and Ethan Zuckerman's post about Eli Pariser and Filter Bubbles, both providing excellent background reading for what I'm pushing here.

But how does one spot the stranger next door? Well, she's somehow different. Maybe the emergent social-semantic web tools can help to find out this. Imagine an interface where users would pick data and people making together a comfort zone representative of their current knowledge and network. First the system would check if this choice is globally consistent, and if yes search the edge of this comfort zone by any convenient follow-your-nose algorithms, and discover assertions related to, but not consistent with the user's current view of the world. So instead of like-minded folks and similar readings comforting my knowledge cocoon, I would see popping up on my dashboard "John Bar, which you might know, has a different view about topic Foo. Do you want to discuss this now?", along with a cool visualization based on the inconsistent triples.

Now that would be an exciting way to explore the social-semantic edges, avoiding the pitfalls of both cocooning and random serendipity. Did you say killer app?

Coreference as a Service

2010-04-08T15:44:00.005+02:00

Yahoo! releases Concordance as part of GeoPlanet API. The aim of this service is to provide equivalence between identifiers for geo entities defined in different namespaces. Quoting Gary Gale on Yahoo! Geo Technologies Blog.

We’ve collected these identifiers and namespaces as a single object, a concordance, which empowers a user to reference each source. You can think of it as a mapping of an identifier in a namespace to its equivalent in another namespace. But it’s not a joining of information; we’re only enumerating the identifiers, not the back-end data or attributes that they describe.

The last sentence is important. The service is agnostic on the data model or ontologies used by the various identifiers publishers. Ontological emptiness makes the service useful.

Another striking example is provided by Ellerdale, reconciliating Wikipedia or Freebase topics with Twitter hashtags to build amazing dynamic pages.

Let's guess that many more of the same will emerge in the months to come.

societas hominum et societas rerum

2010-03-31T08:12:00.005+02:00

Danny Ayers has recently posted a "call to arms" to try and speed up the process of adoption of semantic web technologies. And of course he has triggered the usual bunch of complaints about it. Tools are too technical, stuff is presented by geeks for geeks, data are boring, we need betteer user interfaces etc. Among many smart but technical proposals, basically adding to the general complexity issue they are supposed to solve, I will pick up this very simple one by Karl Dubost.

ACTION : Tell a story to people

I've thought about it, and here comes the best story I've come to imagine, although I'm neither a good story teller, nor good at building user interfaces. I'm just good at metaphors.
The Web is a social technology. What have been the killer Web applications so far? e-mail, blogs, Facebook, Twitter... all social stuff, whichever version of Web you call it. People understand what social entities and social links are about. So, let's tell them the story of the societas rerum (society of things) interconnected the same way as, and interconnected with, the societas hominum (society of people). Individuals connected by (meaningful) links. Yes, data are boring. Instead of the technical linked data cloud, let's show a living Web of people and things. What's in there, what it's all about : people and organisations (FOAF), places (Geonames), books (DBLP), products and services (GoodRelations), events etc. In a nutshell, the story of the Semantic Web is the story of the Social Web extended to things. And it's already there, in many ways, even if not (yet) implemented in the RDF technologies stack. Look at every web resource you get at, and ask : is this resource intended to represent and describe one definite thing? Has it a focus (see previous post)? Is it socially linked to other similar resources? If the answer is yes, then this resource participates in the societas rerum. If moreover it's linked to resources representing people, it's also participating in the societas hominum.

About the title, some will ask : why latin? Simple answer : I've been through seven years of latin classes in high school, so I have to use it somehow and show this off a little. More complex answer : Open a latin dictionary, and figure out the original scope of "societas" and "res", and if it's properly translated by "society of things". In fact I found out after forging this title that those concepts (in latin) seem to have been introduced by Antonio Gramsci. Orthodox marxists will forgive me to use them out of the original context, a bit of which is copied below. More to be found here.

One must conceive of man as a series of active relationships (a process) in which individuality, though perhaps the most important, is not, however, the only element to be taken into account. . . . The humanity which is reflected in each individuality is composed of various elements: 1. the individual; 2. other men; 3. the natural world. . . . Each one of us changes himself . . . to the extent that he changes . . . the complex relations of which he is the hub. . . . If one's own individuality is the ensemble of these relations, to create one's own personality means to acquire consciousness of them, and to modify one's own personality means to modify the ensemble of these relations. But these relations, as we have said, are not simple. Some are necessary, others are voluntary. . . . It will be said that what each individual can change is very little, considering his strength. This is true up to a point. But when the individual can associate himself with all the other individuals who want the same changes, and if the changes wanted are rational, the individual can be multiplied an impressive number of times, and can obtain a change which is far more radical than at first sight seemed possible. . . . Up to now the significance attributed to these supra-individual organisms [that the individual is related to] (both the societas hominum and the societas rerum) has been mechanistic and determinist; hence the reaction against it. It is necessary to elaborate a doctrine in which these relations are seen as active and in movement, establishing quite clearly that the source of this activity is the consciousness of the individual man who knows, wishes, admires, creates . . . and conceives of himself not as isolated but rich in the possibilities offered to him by other men and by the society of things of which he cannot help having a certain knowledge.

FOAF focus

2010-03-25T19:06:00.003+01:00

I pretty much like the new property Dan Brickley introduced as the next addition to FOAF. For what it does, see Dan's explanations yesterday on LOD forum. The rationale is clearly set:

Because conceptualisations of things as SKOS concepts are distinct from the things themselves. If this weren't the case, we couldn't have diverse treatment of common people/places/artifacts in multiple SKOS thesauri.

I let you enjoy the rest of the post, and will simply add that indeed, it's addressing in the specific context of interoperability of SKOS and FOAF the very issue we've been speaking about here for years. Things are distinct from their conceptualisations, and we need a way for various representations to focus on the same thing they are about. There is still a step further, though. The thing itself is present in the information system only through representations. The URI for the thing itself is the best proxy we can get for it in the system, but let's assume with Dan and FOAF'ers that it's somehow closer to the thing itself than concepts in thesauri, and therefore allows the latter to focus on the former. And certainly I'm delighted with the metaphore of the focus, which is yet another avatar of convergence, like the spokes of the wheel I try to keep rolling here. In french, either spokes of a wheel or converging rays of light are called rayons.

Representation as translation

2009-11-29T23:14:00.008+01:00

Words know more about themselves than we generally do, and one should always take the time to explore their etymology. Take representation, a word which is a bone of contention as soon as linguists, semioticians, ontologists, librarians and Web geeks happen to meet, and look back for a minute at its latin origin. Repraesentatio is built on praesens, which has kept in both french présent and english present its double meaning of "being here and now" and "being given". Re-presenting is therefore giving or making present again, and repetition of the praesens is important to notice. Whatever the representation stands for, signifies, means, points at, suggests ... in one word, gives or simply puts us in presence of, here and now, the praesens has been (re)present(ed) already before, somewhere else.
And since the story of representations is so old, and the beginning of the story so misty, let's assume that in the long chain of representations, each new one is leveraging previous ones, and it's turtles all the way down. So, instead of wondering about the untractable issue of the first presentation, why not focus on the process through which one representation is emerging from previous ones. This process has a name : translation.
In "Traduire - Défense et illustration du multilinguisme" (published may 2009, only available in French so far), François Ost presents the multiplicity of languages as a benediction for the life of thought, and calls for translation as our needed common language and new paradigm. This rich and thoughful book is a must read is your French is fluent enough. I cannot in one post pretend to cover all it brings about, but just re-present here a few main points, enough to show the convergence between Ost's thesis and the line of thought we've been defending here for years.
Primo, as indicated in introduction, every text or production of language is the result of a process of translation, and this process is not only happening at the borders of languages, but inside the language itself, and not only between dialects and individual expressions, but inside the mind of the locutor herself. The dialectics of the "what do you mean?" - "in other words" is not a bug of the conversation, it's definitely a constitutive and essential feature of efficient language.
Secundo, translation, at least when it's a good one, is not necessarily an entropic process through which the original meaning is degradated and betrayed. The meaning, or whatever you want to call the praesens in the original (and I will indeed call it praesens hereafter), is not necessarily lost in translation. If the translation is good, it's also present in the re-presentation. More, this new presentation is likely to enrich the original one, and maybe help to understand it better.
Tertio, to keep the praesens alive, we need to re-present it over and over again. Translation is a never-ending story. And the apparent paradox is that we need to do that the more for things considered to be untranslatable. Ost quotes there Barbara Cassin : L'intraduisible, c'est ce qu'on n'arrêtera pas de (ne pas) traduire. Saying the praesens is untranslatable means simply that no presentation is exhausting its praesens, and new re-presentations are needed to get new viewpoints enlightening the previous ones. Pretending to achieve the final representation which rules them all is falling back again into the arrogance and stupidity of Babel's Tower builders, who had lost the meaning by forgetting the diversity of languages. God's action was then not a punition, but a liberation from this deadly road of the unique thought, as Ost shows in the first chapter of the book, a brilliant hermeneutic analysis of Babel's various translations.

Porting the translation paradigm in our local metaphore is quite easy. The wheel is the never-ending story of living knowledge and languages. So many spokes, so many directions to look from, converging in the untranslatable hub which is beyond, but praesens in all re-presentations. But the translation paradigm is what was lacking to get the wheel rolling. As Umberto Eco put it about Europe : Translation is our common language. Indeed, and to put this paradigm into action, each one of us engaged in the process has to learn several languages, in order to be able to look at one language with the eyes of another. Because no one undertands her own language from inside it, and there is no meta-language to rule them all.

Last but not least, the ethical aspect of the translation paradigm : any other language is the language of one other, including mine. In translation, I learn not only to look at the other as myself, as an alter ego, which is still looking from my own viewpoint and measuring with my own metrics, but to look at myself as another, ego alter. Discovering the other-ness, the alterity inside myself, my own language, my own view of the world, is indeed a paradigm change that we all need.

Social networks status update

2009-09-14T12:32:00.003+02:00

For those who care, and since I've mentioned a couple of them in the past two years, here is without comments on the why's and how's, the status of my current, past and potential online accounts on various platforms.

Alive and updated on a more or less regular basis : Faviki, LinkedIn, Twitter
Alive but mostly dormant : Wikipedia, WiserEarth
Used and rejected as noxious : Dmoz (10 years ago), Twine (last year)
Tested and forgotten : StumbleUpon
Never joined, and no intention to do so : Facebook
Unknown, and no intention to know more : all the rest, basically

If you stumble on something I forgot on-line, please drop a comment.
If you want to push me (back) to (re)-join X or Y, well, no, thanks.

Asserting subclasses of open ranges or domains

2009-09-14T12:17:00.002+02:00

I had an interesting exchange on Semantic Web list on this issue last week. You can browse the whole thread, but I would recommend answers by Pat Hayes and John Sowa.
Below are extracts of my final answer.

1. There is quite a difference to make between concepts in ontologies strongly defined by domain experts, and targeted at feeding reasoners (e.g., bio-medical or legal ontologies), and lightweight ontologies such as FOAF, VCard, Dublin Core, Geonames ... which are mainly targeting interoperability of data, and of which meaning (if not formal semantics) emerge from usage and population. I can't define formally what a Person is, but I can say that you and I are some instances.

2. For the latter said ontologies, the main objective is to provide guidelines for applications harvesting and managing data. The actual formal semantics of those models is next to nothing, but implementations can reasonably leverage them on the basis of a common sense interpretation. For example the thousands of different data models to represent a person can be re-engineered as so many specifications of the generic class foaf:Person, therefore allowing a shallow, but efficient level of data interoperability.

3. There is no more, no less semantics nor potential usability in declaring skos:Concept to be in the range of dcterms:subject, than to declare foaf:Person to be a subclass of foaf:Agent. "Dont acte"

For some other ill-defined property ranges in the Semantic Web popular ontologies, another path would be to use enumerated classes, or in a more flexible way, to indicate a published vocabulary maintaining a reference enumeration. For example when LoC publishes later this year the authoritative ISO 639-2 list of languages as a SKOS Concept Scheme, the range of dcterms:language could be restricted to the values in such a list (using e.g., a restriction on the value of skos:inScheme). This would avoid Dublin Core to go through the painful task of defining formally the class dcterms:Linguistic System which is the current specified range - with the same lack of definition as foaf:Agent. Referring to some authority is certainly the best way to deal with the issue here. We (DC) don't know what a language is, go ask ISO 639-2 folks, apparently they know because they are able to provide a list.

From meaningless to ambiguous

2009-08-10T18:06:00.007+02:00

A previous post looked at concepts as names species. Several threads about URI meaning and ambiguity later, including on www-tag@w3.org list this post from Karl Dubost, and with in mind again names and concepts as living things, here is yet another variation on morning, noon, and evening mountains.

Morning names, meaningless, useless
Names at noon, meaningful, useful
Evening names, abused, ambiguous

This basically is the life cycle of names from no use to use and eventually abuse. Use leads to meaning, then abuse leads to meaning overloading. This is the natural course of things. And since URIs are names, this is also the natural URI life cycle. So let us use what is meaningful while it is if we want meaning. Be prepared to ambiguity at the end of the day, but if evening ambiguous names have been abused, it does not mean they are useless.

URI species

2009-07-30T23:25:00.001+02:00

The debate about proliferation of URIs representing the same thing keeps on rolling on various Semantic Web lists, going back again and again to the same questions. How does one discover existing URIs for a thing, if any? Is it a good or bad practice to mint a new URI for a thing which already has one? How do one link URIs identifying the same thing? Many smart and conflicting answers have been given, largely depending on the viewpoint on Web architecture and the main use of URIs in the mind of their authors. Web pragmatists and linked data evangelists tend to consider that proliferation of URIs is not necessarily a good idea, but something we are bound to live with, whereas experts in knowledge representation tend to consider it should be avoided by all means. Trust, persistence, quality of resource descriptions, use and abuse of owl:sameAs have been discussed over and over, with no obvious technical answer.

Since life provides the oldest, proven, efficient ways to store, maintain, replicate and use information, I've tried to figure if we could not learn from biology. Interestingly enough, biologists are not more able to come to a consensus about what a species is than Semantic Web gurus to agree on what is behind a URI. Somehow, the two issues are very similar. They deal with persistence of information over time. With the disclaimer that I am not a biologist, let me assume here the definition of a species as the set of individual expressions of some common genetic pool. Protection and persistence of the species genetic pool is the main occupation of any form of life. Strategies to achieve this goal present an awesome diversity, but in this variety one can find some constants. Among those are the basic facts that individuals are bound to a short life span, so the protection of the genetic pool is best achieved by assuming mortality of individuals, and ensuring duplication and replication of the information in as many individuals as possible. Not by defending a single representation behind firewalls.

How does that apply to the Semantic Web? A URI, along with the resource description it provides, can be seen as an individual expression of a species concept. As any human artefact, or any living individual, or any physical manifestation in this world, this expression is bound to be a transient. The agent who created and maintain the URI is bound to disappear, among other things. It will be less costly, as life tells us, to have copies of the information in as many expressions as possible all over the place, than to protect this specific one. Consider a URI not as the unique representation of a thing, but as an individual expression of a species.

Common Tag

2009-06-30T10:07:00.004+02:00

Based on Common Tag specification and various APIs around, there are certainly a lot of easy next steps towards interfacing more efficiently the free tagging and linked data universe. For example it should not be too difficult to build an interface allowing the mapping of Twitter hashtags to DBpedia URIs, based on both Twitter and Zemanta APIs. Faviki could open this path.

Everything is a thing, everyone is many

2009-06-10T23:43:00.003+02:00

So I'm now on Twitter, following a couple a people, hoping some interesting bits and pieces will float around to my shore. And well, some have. For example this interesting piece on Multiple Personas. What Silona writes there on the essential multiplicity of a person can certainly also apply to things and representations. We know more or less from inside our multiplicity and ambiguity, and the importance of keeping multiple personas revolve around our fundamental and essential emptiness. But we've lost most of the time the capacity to look at things the same way. As Jean Rousselot put it, we are not simple enough any more to "enter things as things can enter things"

Il faudrait pouvoir entrer sans frémir
Dans les choses
Comme les choses
Entrent dans les choses.

The poets are the ones able to enter things, experience their mutiplicity, and show how they appear to us as multiple personas.
We should look at the necessary convergence of the social and semantic web(s) with this paradigm of multiple personas in mind.

sameas.org

2009-06-09T23:18:00.003+02:00

sameas.org is quite an implementation of hubjects for the linked data universe. It relies still a bit too much on owl:sameAs, but I begin to believe that owl:sameAs eventual semantics will be the one applications make of it. Only reasoners in closed universes will apply owl:sameAs for what it is in the standard (strict identity). Open Web and linked data cloud will use it as "follow-your-nose" hubs to switch from one representation to another and aggregate information.

WE are the hubs

2008-11-28T10:25:00.003+01:00

We've spoken a lot here about identifying and linking things and data about things. But 2008 will stay as the year of linking people. Clay Shirky exposed that brilliantly in his book "Here Comes Everybody"
As hundreds of millions of people, I've engaged in a few social networks this year. Not that I was not in some on-line communities before. In 1999-2000 I was Open Directory editor, since 2001 I've been a lunatic Wikipedian. But it was not those fancy Web *.0 social networks making billions of dollars. I've never been in Facebook or MySpace or the like, never going over this a priori reluctancy to join in noisy, aimless social chatter, exchanging images, music and recipes. No thanks.
Nevertheless ... I joined LinkedIn in January 2008, mostly to update my address book. At the time there were 17,000,000 people "In". Now the figures are over 30,000,000, or so they say. At the end of 2009 it's bound to be 1% of mankind. But LinkedIn is mostly an ego-booster. The main purpose of being "In" is very selfish : look at how efficient and professional, how many people I'm connected with etc. There are groups, but they have no real social activity as far as I can tell. So I keep my LinkedIn account for what it's worth : a free human resources directory.
In spring I had a try at Twine. With good marketing, they attracted a lot of smart, brilliant people. It was an interesting experience, but mostly unfocused and time-consuming. Twine has no particular purpose beyond conversation. I was quickly fed up with that, so I left.
My favourite these days is WiserEarth. I was very impressed by the clarity of purpose, the quality of information, and the spirit of the community. Of course the numbers are still small, less than 20,000 to-date. But you're most welcome to join.

Open GUID : anchoring hubjects

2008-09-26T09:28:00.006+02:00

Jason Borro has announced yesterday his Open GUID initiative on the Linking Open Data forum. After a first day of open discussion, it appears that he has came with the right implementation of hubjects, and moreover with a great metaphor. Hubjects must be anchored in signs, bot human-readable and computer-readable. Here is what I come with this morning.

Everything is a Sign

2008-07-15T23:41:00.003+02:00

That is, every thing is a sign. The first and main function of any language is to allow division of the world into "this" and "not this", based on some interpretation of data received from the world. Such an interpretation of data as signs is the basic form of semiosis, a process performed for quite a while by humans, and for many more ages by animals before them. It can now be performed by machines or information systems (roughly, computers connected to data acquisition devices). The aspects of this process can be defined as following.

SALIENCE : Capacity to separate as meaningful (significant or salient) a certain data set from the continuous data flow we get from the world through our perceptive experience, be it direct through our biological senses, or indirect through one or more several levels of mediation : reading data gathered by instrumental devices, compilation of such data over time, texts interpreting those data.
SIGNIFICATION : Capacity to consider the salient data set as a signifier conveying a particular meaning (signified), based on some characteristics such as spatial connectivity, permanence in time, regularity of patterns, similarity with other data sets previously interpreted and stored as signs, or anything the interpreter sees fit by its own rules and general view of the world. The core and essential meaning assigned is generally permanence, existence of a "thing" underlying the "sign". The thing is the signified associated to the signifier which is the data set.
REPRESENTATION : Translate this sign/thing (both signifier and signified) into some proxy in a representation language allowing storage and retrieval for further use. Typical forms of representation include assignation of identifiers (symbols, icons, names, code numbers), description of the signified, and its connection to pre-existing ones through classification, typing, or any other kind of association or linking.

The above analysis can be set as the basis for a general semiosis framework applicable to natural languages (human or otherwise), formal languages used in our information systems, and scientific languages (theories in physics, biology). This framework, while keeping agnostic at the metaphysical level on the ontological status of things, will hopefully help to provide a solid theoretical foundation to the emerging semiosphere, the network of human knowledge and languages and information systems.

For use of this approch in the Semantic Web area, see a first cut ontology here. More to come.

Own your identity

2008-05-21T14:21:00.001+02:00

ownyouridentity.com is a blog about owning your online identity in a world with an increasing amount of software that wants to own it for you. It's written by the chi.mp team and friends.

Managing Co-reference (Was: A Semantic Elephant?)

2008-05-18T23:39:00.002+02:00

One more public thread on SW list on our favourite issue. But some interesting points to note in the current discussion, well summed up by Aldo Gangemi at mid-course.

We definitely need some property or mechanism, weaker as owl:sameAs, to assert that two URIs have similar referents.
The semiotic aspects of co-reference are more and more acknowledged, even by formal logic gurus.

Hopefully this thread will eventually have some follow-up on some standardization track.

URIs for languages

2007-10-09T12:05:00.000+02:00

I've eventually given up trying representing hubjects at all, at least for the moment. I had a serious try at it at lingvoj.org. But after discussions in the Linking Open Data forum, I eventually surrendered and published the languages description in a way conformant to W3C recommandations for Semantic Web architecture, with content negociation, 303 redirects and the like. I've even suppressed the previous post here saying otherwise, which would be now full of dead links and would bring about confusion.
So we'll see how this flies. Feed your favourite tool with the URI http://www.lingvoj.org/lang/zh, and figure by yourself if it provides a useful description of the Chinese language, both for humans and machines.

Using owl:sameAs in Linked Data

2007-07-24T10:05:00.000+02:00

It's been a very long and interesting thread on Linking Open Data forum and elsewhere, about the use and semantics of owl:sameAs. I just suggested the following best practices :

Assertions such as "a:foo owl:sameAs b:bar" should be grounded on some form of agreement of the owners of a:foo and b:bar, on whichever basis they both decide to agree.
For outsiders (owning neither a: or b: domains), such agreement could be shown by the presence of the assertion in symmetrical way in both domains, each domain using its own URI/resource on subject side, and the other's on object side, that is :
(a) asserts "a:foo owl:sameAs b:bar"
(b) asserts "b:bar owl:sameAs a:foo".
If one side (a) pushes the assertion first, the other side (b) should be at least made aware of it by (a), and is entitled to say she agrees or not : (a) says that "a:foo owl:sameAs b:bar", but as the owner of (b), I do not necessarily agree. Such lack of agreement could be implicitly entailed from the absence of the reciprocal assertion on (b) side.

Granted, from a pure logical viewpoint, those assertions are strictly equivalent since owl:sameAs is a symmetrical property, but from a social/trust viewpoint, having each side declaring it in a specific direction could be interpreted as a formal proof of agreement. It's what have been done e.g. between DBpedia and GeoNames. The title thread shows once again by its sheer length, and if necessary, that there is no universal way to ground such agreement, which belongs to the realm of language and social communication.

A journey to Data Mountains

2007-04-24T22:14:00.001+02:00

Seems about time to revisit a famous Zen aphorism (more verbose translation here)

Morning mountains, only mountains
Noon mountains, more than mountains
Evening mountains, simply mountains

How does this apply to what we have been speaking about here? We've tried in the morning of our ignorance to pile up mountains of data, and had hard time making sense of them.
In the broad daylight of our powerful abstract thought, both intuition and logic, we found out that useful data were data about some thing(s). Making explicit the things data are about was really the way to follow to organize, understand, search, query, in a thousand ways make data more useful, more meaningful. So we went through those mountains with this "about-ness" in mind, and they looked indeed more than mountains, they looked like information about things. We called it classes, properties, relations, and started re-engineering data in all sorts of smart ways : metadata, RDF, topic maps, ontologies and the like. Happy to bring more and more meaning into data, we called it knowledge, and we thought we had found answers to some fundamental questions, discovered the information lost in data, and the knowledge lost in information. Captured the mountain's spirit.

Then came the time to harvest, to weave it all together. I had knowledge in my information system, and so did you. Or so we figured. But looking into your system, I found only data, and so did you when you looked into mine. Where are the things gone? Where is the knowledge hidden? Only data, which we had to figure again together how to weave.

So we'd not captured the mountain's spirit after all. But we did not travel in vain, because we've felt it blowing by. We know it's hidden somewhere beyond the data, beyond information, beyond what we have called knowledge, and that without this spirit our data would be completely meaningless and useless indeed. And what is more, we have at least found a piece of wisdom lost in knowledge : data are only data.

A bit of Chinese

2007-04-13T18:52:00.000+02:00

I've been dreaming about learning a bit more of Chinese than the few characters I've been playing with ever since I discovered the excellent introduction by Kyril Ryjik's "L'Idiot Chinois", around 1980 or so (this book is unfortunately sold out now). I've decided that now is the time to learn Chinese, for all sorts of obvious reasons. Hence the extract of the original Chinese text of the now famous "wheel and hub" quote in this page. If your browser does not support Chinese characters, you should do something about it right away.
I've tried to come out with my own translation. Note that I got rid of any capitalization, because Chinese has no notion of Absolute Capital Things. The concepts represented by Chinese characters are most of the time both concrete and abstract, generic and specific. No definite or indefinite articles, no clear distinction between grammatical nature and function. Depending on the context, the same character may be translated as a noun, a verb, or adjective.
In a way, Chinese characters are by nature ... hubjects.

Adieu to Published Subjects

2007-02-23T10:14:00.000+01:00

I've learnt those days that the OASIS Published Subjects Technical Committee, which I've chaired for two years from its foundation in August 2001, was closed. Actually it was officialy closed by OASIS in November 2006, but I had not received any notification from anyone. Sounds like learning the death of an old friend months after.
Actually the activity of the TC was dormant since the publication of its first and somehow unique deliverable Published Subjects: Introduction and Basic Requirements. This output does not seem much after two years of work, but it figures there was not much more we could achieve. In a recent private exchange about the future of Published Subjects, Patrick Durusau, who chaired also this TC after 2003, still wants to believe that it is not the end of it, that the work has stalled mainly by lack of task force, but maybe anyway this TC was a case of premature specification.

I think that the notion of a published "identification" of a subject, whatever you want to call it, is probably a good idea, so long as anyone can add their identification of the same subject. On the other hand, a notion that this *is* the identification of a subject, well, that leads to losing propositions like the stuff you find at Swoogle. How many different identifications of person are there?

I already set this question here two years ago. Amazingly enough, the figures does not seem to have changed since (399 answers by today).
I take the opportunity to point to this paper by Patrick. If you have not figured out what a subject can be, even after an extensive reading of this blog (or don't care going into so much reading) this is a must. Short, clear and to the point.

Linking Open Data

2007-02-06T12:15:00.000+01:00

This is a challenging project for Semantic Web technologies. Weaving together open public data, such as Wikipedia or Geonames, and public ontologies and vocabularies such as Wordnet, etc. Of course I had to be involved in that. But consensus will be hard to achieve. Initiators are folks from Leipzig and Berlin universities, involved in dbpedia, a project to RDF-ize Wikipedia content.
I've pushed the idea that linking concepts from different schemes should not be done on the basis of too strong ontological commitment, but of some kind of loose coupling using e.g., SKOS mapping vocabulary, and why not blank concepts. This proposal has not been well received, to say the least.

Chris Bizer says:

I'm in general against using bnodes for anything! They should be deleted from the RDF spec and they are especially harmful in a linked data context, where everything should be dereferencable.

And Richard Cyganiak adds:

Yes, sure ... I understand why you want to introduce the blank node. But I don't like it. Why do you generate data? You want it to be useful. How does this blank node increase its usefulness? It doesn't. It's just a fig leaf to cover up the fact that your model is just an approximation of the real world. But we know this. Every model is. And these "semantic rubber bands" don't change this fact -- they just make your data harder to work with. Be bold! People who want to re-use your data will learn to work around its quirks and idiosyncrasies. Dealing with the quirks is a part of re-using data, it always was, and it always will be.

So much for my hubjects ... but this is not the end of it. More to come.

Changing blog title

2007-02-06T12:08:00.000+01:00

I know, changing names, like changing URIs, is a silly idea. Cool names never change. But I decided yesterday to re-activate the original univers immedia in French. And since 'The wheel and the hub' has definitely been for a while and certainly will continue to be, the motto of this blog, it had to make its way up to the title.

Every subject is a blank node

2007-01-02T10:21:00.000+01:00

Two discussion threads made me move a step forward towards a general theory of blank nodes. One thread I already mentioned is about languages. The other one was started here by John Black on Semantic Web list, about representation of concepts having contextual semantics, such as "I', "You", "Here" etc. Using a blank node to represent the context is the solution I propose today here.

Where do I go from here? In RDF, URIs are good at defining unambiguous property values, in other words objects, including type. But very often, and maybe most of the time, the individual subject (in both meaning of subject of an RDF triple, and topic maps subject of conversation) is best represented as a blank node bearing all kinds of identified properties, but none of them conferring absolute identity. This way, it's left to applications to figure out identification rules, in other words which property or boolean combination of properties they want to consider as identifying or not. Based on some set of application rules, two subjects can be considered the same, whereas based on other rules, they are considered different. This is actually how it works in the real life and natural language, where many subjects have inherent ambiguity. In order to deal with this ambiguity, no absolute identifying property should be asserted for such subjects.
This may provide a way out of the debate on URI ambiguity. URIs should not be ambiguous, so they should be used for unambiguous subjects. But as long as we deal with real world subjects which are inherently ambiguous, like persons, places, contexts, languages ... they should not be attached identifying URIs.

Classifying is hard, tagging is worse

2006-12-29T12:05:00.000+01:00

My work for Mondeca has been for years to help building classification schemes, ontologies and the like for a variety of customers. Most of the time this means formalization of implicit ontologies they already have in their data. And I don't have either to make any decision about actually populating the schemes, this task is left to human editors or automatic text mining engines. I sometimes take care of automatic migration of legacy content, but following rules decided with the customer. I'm very happy with all that, because I'm not good at classification. I tend to see so many subjects in anything, any interesting resource to classify seems so multi-dimensional that choosing a category always brings me to the fringe of undecision, and any decision I eventually make about it seems always arbitrary. Comes maybe from an ancient traumatic experience as Open Directory editor.

Sounds familiar? I already hear the folksonomy people crying : "Hey, of course, that's why tagging is so cool". As far as I am concerned, tagging is worse, it means more arbitrary decisions, because not only do I have to choose a category, I can choose more that one, or none at all, and I have to figure them myself. Way too many decisions ... That's why my browser bookmarks and email folders are a mess, why I have no del.icio.us account, why my Technorati profile is so low, etc ...

Beyond my own decision difficulties, there is something to be added as this now long discussion obout ontologies vs tagging. What I've learnt in science is that a good theory is a falsifiable one. What you assert using an ontology, whatever language or framework with declared formal semantics, is falsifiable. No formal semantics, no notion of true and false, hence no falsifiability. In other words, and to make it simple, an RDF assertion can be declared or inferred true or false vs a given ontology, a OWL class can be proven unsatisfiable etc. Nothing of the like with tags. Assignation of a tag cannot be proven true or false, or inconsistent. Tags are not falsifiable.
By the way, the same distinction is to be made for RDF vs Topic Maps. Topic Maps are not falsifiable, because they have no formal semantics. Now the question is to know is falsifiability, which has been proven to be critical in science, is also critical in information technologies.

That said, since the new Blogger version enables easy tagging (maybe the older version did also, but was never aware of it), and since there is now quite a bunch of posts on univers immedia, I decided to be brave and start tagging them, as thoughtlessly as possible. Starting by the more recent ones, I then shifted to the most ancient, a good occasion to revisit them if nothing else. The result you see on the left under "What". First impression is of course there are too many of them, but I will try to keep up that way throughout the blog just to see how it flies, then maybe keep only the most frequent ones if I end up with a too long list.

OWL ontology for identity on the web

2006-12-27T15:58:00.000+01:00

This paper by Valentina Presutti and Aldo Gangemi at SWAP2006 begins with a clear introduction to the issue of resource identity, and the ambiguity of the term resource itself. Then it goes on with a very smart OWL model attempting to articulate the various aspects of this concept. Maybe too smart and conceptual to become really popular, but interestingly enough, it goes against the popular Semantic Web assumption that URI can actually identify "non-addressable things", and is rather in the line of letting the referent entities outside of the identification framework.

The definitions of resource that can be found in literature show ambiguity, making the issue of handling the identification of a web resource very problematic.
Our approach restricts the nature of the web resource to that of a computational object. This choice is motivated by the fact that a resource is something that has to be addressable, and things like cars and people are not addressable for their nature. Hence, it is wrong in principle to use the same mechanism of addressing for entities that have such different sorts.

Migration to new Blogger version

2006-12-27T15:37:00.000+01:00

I took the opportunity of this migration to change the layout template. The new one seems more readable, and anyway I was fed up with all those dots. I like this little architecture piece on the top left corner. Actually I think it's a lighthouse, since the template is called "Harbor", but it also looks to me like an observatory platform opening on the sky, "useful by its opening and central emptiness" ... well in the spirit of univers immedia.

The list of contributors does not show anymore, they have to do something about their Blogger account to be able to post again.

A couple of things I've been about lately

2006-12-27T00:13:00.000+01:00

I've been silent here for over two months now, my blogging time devoted to the Mondeca blog in French Leçons de Choses. But there is a couple of things I've been working on, worth mentioning.

I've exchanged with Michel Biezunski on his Data Projection Model , and found out that its genericity and simplicity made it easy and straightforward to express the structure of Mondeca ITM, without the borderline hacking needed when using either OWL-RDF or XTM for the same task. Now open questions: What will happen with that model? Who will see the benefits over languages already in this space, and singularly over RDF? Who will build tools supporting it?

Been wondering if a semiotic approach could shed some light on our thoughts on referents, and came out with a RDF semiotic triangle. The URI is the signifier, the RDF description is the formalisation of the signified concept associated with the URI. The referent is out of the language and signs realm, and should stay there. In this approach, attempting to achieve a representation of the referent, even using tricks as blank resources or hubjects of any kind, is therefore a recursive trap and actually a non-sense. So any declaration of same-ness or identity of referents should be avoided. Only concepts bear identity, not their referents. From that point on, came to the idea that linking different concepts/signs (URI + RDF description) which humans consider to have more or less similar referent will take the form of processing rules, more than declarative semantics.

Thanks to Jakob Voss for this post in a long thread on public-esw-thes list, which really triggered a kind of illumination about this. As an example, trying to say that my SKOS concept a:Restaurant has the same referent as your OWL class b:Restaurant through any RDF declarative relation between those two resources shoud be avoided. But I can set in my system a functional rule expressing that any document of which subject is an instance of your b:Restaurant class will be indexed against my a:Restaurant concept. The referent is represented nowhere, but it is acting at the core of this rule.

Actually we have this very indexing rule mechanism working in some Mondeca applications, and I have submitted a paper to XTech 2007 about it. More to come if ever the paper is selected.

Lately, got interested again in triggering some process to have languages available not only as tags to use in XML, but as proper RDF resources. This is an old story tracking back to OASIS Published Subjects Technical Committees, and singularly PSI for languages. Track this topic on ESW Wiki, and see here for ongoing thread and more explanations. There again, my proposal is to forget absolute identification of a language by a URI. Concepts identified by URI are the properties and property values than can be declared for a language, and let applications decide on which properties are useful to them. No absolute rule saying that two descriptions refer to the same language.

Leçons de Choses

2006-10-27T12:36:00.000+02:00

My blog activity lately has been dedicated to launch the new Mondeca Blog - yes it's in French. Sorry about that.

Geonames enters the Semantic Web

2006-10-14T00:34:00.000+02:00

I'm quite happy of this. The collaboration with Marc at geonames started as a simple deal : provide the ontology, said he, and I'll provide the Web Service. So did I, and so did he. This is a fantastic Web 2.0 place to play in. It already had Web Services and wiki using Google Maps, and now he has the SW interface ...

Back to Earth

2006-10-03T15:46:00.000+02:00

I've been quite silent here lately. Put more focus on actually working stuff than theoretical musing, and singularly on various geo-unameit technologies such as geocoding, geotagging, geo microformat, and the collaborative databases using them like geonames, wikimapia ...
Places are the most fascinating use cases when it comes to identification and description, and all those technologies and their ability to interface with each other tend to prove that information about some place can be aggregated without any consensus or explicit declaration of what this place (or a place, in general) actually is, but by providing hubs between data, and interfaces putting together data somehow relevant to this place (such as Google Earth, Google Maps API and the like). Geonames web services provide a good example of this.

In defence of 404

2006-08-07T18:22:00.000+02:00

Following the announce on the Semantic Web list of the publication of RDF geographical codes by french INSEE, a lively debate with Dan Connolly about access vs description.

More thoughts on that Blue Glass

2006-07-26T10:01:00.000+02:00

John Black commented on my previous post, providing links to interesting pieces of thoughts. Anatomy of a Reference and Ambiguity and Identity are certainly in the line of what we try to entangle here.
Let's put those pieces together. John's blue glass, physically tagged with its URI is a clear example of the difference between access and naming as explained by Pat Hayes. What is accessed using this http URI is an image of the blue glass, but the URI is intended to name the glass itself. Tagging physically the blue glass with a URI sticker or a bar code is something very close to what Pat calls ostention, but it's not the silver bullet to kill ambiguity.
As John clearly points, when you stick a tag somewhere in the physical world, you still need interpretation to know which part of the world is tagged this way, since the world is not "naturally" divided, things and their limits are always the result of some mental operation of division. So a common interpretation of the tag needs a common understanding of the limits of things, and having a common understanding of classes of things, and which kind of tags you put on which class of things is really useful. This is something well known in geographical maps. On ill-designed maps, names are not printed properly, and it's often unclear what (town, river, mountain ...) is named. In well-designed maps, there are a lot of implicit or explicit disambiguation tricks, such as fonts, colors, position of the name vs the named feature etc. One has to know all that to make sense of the map (actually many people are not able to make sense of a map properly). When you come to the ground, you have similar physical tags indicating towns, rivers, streets and house numbers, and you also need similar knowledge to construe those tags in context : this kind of sticker is for a town, that kind is for a street, and so on. And even so, what is the limit of a town, a street, a valley or a mountain remains basically undecidable.

Ambiguity, Ostention and Description

2006-07-25T12:42:00.000+02:00

Pat Hayes' In Defence of Ambiguity, presented at IRW 2006, has been on my desktop for weeks, and I take it as the most challenging food for thought currently available about the Semantic Web. If you have not yet read it, you should now.
There is only one point on which I would argue. Pat holds that reference can be made by ostention (gesticulation showing what you are about) or description. All Pat writes thereafter about description being inherently ambiguous, I strongly agree with : disambiguation being a contextual process, the more precise the description, the more ambiguity you get, and so on.
But I would hold that ostention is as ambiguous as description, so that reference is ambiguous in nature whatever the way it's done.
Suppose I am holding a book and ask you : "Have you read this?". The reference to "this" is by ostention, since I seem to hold and show "this". But the "ostentatum" indicated by "this" is actually some copy of some edition of some book. Does "this" refer to this specific copy, which happens to be my own personal copy (maybe annotated in some way), or is the referent the particular edition of which this specific copy is a sample, or is it the abstract entity, the book independent of any physical support, of which what I am currently holding happens to be some physical avatar? Every one of those interpretations is meaningful, and only the context of the conversation might disambiguate. So even with ostention, there is ambiguity left.

Wikipedia's semantic cow paths

2006-06-20T19:47:00.001+02:00

I've been quite silent here on this blog for two months, and meanwhile resumed a bit of my Wikipedian activity lately. Although I'd been an enthusiastic early adopter of Wikipedia back in 2001, I have a poor and episodic editing history so far. But every time I've been coming back to the editor dashboard after months or years of inactivity, I've been amazed by the tremendous qualitative growth of the toolkit made available to users. Wikipedia's growth has been stressed again and again in terms of quantity and quality of articles, languages, editors, popularity as a reference resource etc. But was has not been stressed enough is the parallel growth in terms of features supporting better search and editing. And many of those features are in fact adding a quality of information which makes it ready for semantic parsing, and easy RDF re-writing. The basis of it all is a sound use of URIs, names and namespace.
For example http://en.wikipedia.org/wiki/Volcano defines without ambiguity the unique page dedicated to this geological feature, while http://en.wikipedia.org/wiki/Volcano_(disambiguation) is a hub to potential homonyms such as http://en.wikipedia.org/wiki/Volcano_(film). Links are provided to similar resources in other languages such as http://fr.wikipedia.org/wiki/Volcan. One can reasonably use any of those URIs to identify the concept "Volcano". But what about a class Volcano? Here come Wikipedia categories. http://en.wikipedia.org/wiki/Category:Active_volcanoes is ready-made for a class, and parsing the page will give you easily the list of instances, with a link to the full description page. This description itself is formatted using templates such as "infoboxes", so that a page in a category "Active Volcanoes" will yield standard properties in a standard format. Easy to turn this into a data base, and if one interprets the infobox elements as so many properties, turn it into a RDF description, and the infobox structure itself in a RDFS or OWL description of the matching class.
What should we learn from that? That from a collaborative and mostly non-directed process, are emerging cow paths which look more and more like semantic markup, ready to be spidered by smart parsers and tools, either to improve Wikipedia content itself (there are already a bunch of bots and agents doing that), or to extract of this amazing knowledge base any kind of structured data in whatever format, including implicit ontology, like structure of categories, attributes used, and the like. And my hunch is that this process will be quickly much more effective for Semantic Web building than many costly academic ontologies nobody will ever use.

Comment (2010-04-08) : What is described here is exactly what DBpedi a started in 2007

More use cases for nondescript resources

2006-04-11T00:20:00.000+02:00

nondescript is a funny word. Quite sure I did not catch its correct meaning when I first heard it. It has no real equivalent in French. Indescriptible is too strong, it refers to something too extraordinary to be described, whereas nondescript is actually too ordinary to deserve a proper description. Or is it that any description would miss the point? The free online dictionary says : Lacking distinctive qualities; having no individual character or form. Maybe in fact nondescripts remain such because those features which makes their individuality are too subtle to be captured, or this capture would be useless.
Anyway, let's take them as they are : no description. What does a nondescript look like in RDF? Well, easy, it's a resource with no description. No type, no identity, no properties, certainly not even worth a URI. A blank node with no property whatsoever. Rings a bell now? After the previous post, I've come out with more use cases for those nondescript resources, and how natural language uses them as binding points. Examples

John walks through the neighborhood where Ann is working.

:John :walksThrough _:n
:Ann :worksIn _:n

In The Rule of Four (currently reading) Vincent and Richard have different theses about Hypnerotomachia Poliphili. Paul prefers Richard's thesis.

:Vincent :hasThesis _:tV
:Richard :hasThesis _:tR
:Paul :prefers _:tR

Now the "Class or Concept" example comes naturally as just another case

a:Restaurant a owl:Class
b:Restaurant a skos:Concept

a:Restaurant :represents _:x
b:Restaurant :represents _:x

Cloud hidden, whereabouts unknown. (Similar stuff in the early '70s)

Identifying things - blank nodes again

2006-04-04T19:11:00.000+02:00

Still trying to figure if the hubject seeds are likely to grow somewhere, so I dropped one today on Danny Ayers' blog, as a comment on a post itself commenting on another one from Jon Udell where is introduced the cool notion of collaborative aliasing. "What a concept!" will say Jack. And actually, it's no more no less the idea that hubjects can be created out of aggregation of resources being "about the same thing". An aliasing service, which really looks like tagging.
So my suggestion again is here to use blank tagging, that is, allow users, in a simple way, to make all those resources point to the same blank node.
Now something is slowly coming from the back of my mind. I thought for a while we needed a specific and mysterious vocabulary to do that, hubjects and the like. Since this kind of stuff is far from being on the track of adoption, maybe using more popular and less exotic vocabulary, such as dc:subject or something similar would make the whole thing more understandable. Seems there is no formal opposition to declare things like:

http://www.amazon.com/gp/product/B00006RCLH dc:subject _:b
http://labs.oclc.org/xisbn/068981836X dc:subject _:b
http://en.wikipedia.org/wiki/Call_of_the_Wild dc:subject _:b

And actually, any other property could be used as well, such as the following, to take the example from Jon Udell's post
http://upcoming.org/venue/3669/ a:venue _:x
http://eventful.com/venues/V0-001-000150985-3 a:venue _:x

This kind of declaration keeps completely agnostic on what a venue in general, and this particular one actually is. It simply says that the two resources are about the same one.

Identity vs Meaning

2006-03-15T17:52:00.000+01:00

Under this really boring title "The Semantics Are Important", Seth Ladd in his Semergence blog is making a really good point :

The identity is singular. The meaning is relative.

In other words, identity and identifiers can be shared, global, universal, whereas semantics/meaning, such as expressed in a particular RDF graph, is local, relative, context-bound, perspective-defined. And therefore multiple, orthogonal, non-compatible, globally inconsistent.
I like it more and more. This goes along the same lines as Pat Hayes' recent post, and puts again the question of how to deal with context. I'm not sure now, munching over Pat's arguments, that the context always needs to be explicited. I've been working those days on SKOS used to express simplified view of hierarchies (of any kind) in an OWL ontology. In some OWL ontology, one would find

a:SomeRegion a:partOf a:SomeCountry

In a simplified SKOS view

a:SomeRegion skos:broader b:Some Country

Reasoners and RDF stores are happy with the OWL version, search engines, taxonomy managers and the like are happy with the SKOS version. So one perspective by kind of tools/applications. What would not make sense would be to merge them, and entail that a:SomeRegion is at the same time an instance of a:Region and skos:Concept. It is not at the same time, it is one in some application context, and the other one in another context. No problem with that. So what is a:SomeRegion in essence, to use this arrogant word I saw passing in the previous post? Well, it's neti, neti, neither this, nor that. No big deal. Who cares?
Set this question about a week ago on the SKOS forum. An astounding silence has been the answer so far ...

Identity -- some philosophical musings

2006-02-10T15:52:00.000+01:00

Here are some interesting words taken from the link. Follow the link for more. Following, I'll sketch what I am thinking. This is a bit disjoint, but, I think, necessary. It seems that our topic maps are becoming sophisticated enough that we are now able to push the boundaries of subject identities that motivated Bernard to start this blog in the first place. Maybe someone else, or something else (hubjects?) will help resolve some things dealing with subject identity. Possibly longish.

IDENTITY

Crystals appear (on the scene of Reality) -- just like organisms -- always as individuals. Such an individual has a definite Identity that remains constant during its existence. It is, say, A, it is not B, not C, etc. A developing crystal of Salt (growing in a solution) can change its shape while its Identity remains the same. For organisms this applies even stronger. We ourselves (being an organism) seem to have direct experience of our Identity staying the same during all of our life in spite of the fact of the many changes we constantly undergo. Some insects undergo a strong metamorphosis (for example from caterpillar to butterfly) but nevertheless their Identity stays the same. So it seems for every entity, which is an intrinsic whole, that there is something that remains the same, and something else not remaining the same, but always changing. In Philosophy such changes are called "accidental" or "per accidens" in relation to the persistent Identity. This Identity is called the "intrinsic Essence" of the thing, so every real uniform being has such an Essence.

IDENTITY AS A PRINCIPLE

But what then is this Essence?
Where does it abide?
Does it abide outside the thing (as Plato assumed), or inside the thing (as his famous pupil Aristotle assumed)?
And if the Essence is located inside the thing (meaning that the Essence of every being abides in "our world", and not in some external immaterial world transcending the material world), which I consider the most probable position, where in the thing is it located and in what way? Could this Essence be a concrete part of the thing, the "heart" or "soul" of the thing, which implies that the Essence itself would also be a thing (and this thing should of course also have an Essence of its own........Oh my god, where are we going???), or is it in the thing in an abstract way (whatever that means), like a principle?

A background sketch: together with Joshua Levy, I am building a subject mapped social bookmarking application. We call it Tagomizer (tm). It's being fun. But, it's also causing (moi) brain pain. What is a subject? Let me translate. Someone bookmarks a webpage. This means that the URL of that page, and the page title, are sent to Tagomizer, which then paints a form in which the user can add tags (words or phrases for now, images and other objects later), and a body of text taken as a comment. A user can come in later and add more comments or more tags, or remove tags. Tags are a large part of Web 2.0, where folksonomies are breaking out everywhere.

What is a subject? When Tagomizer creates a bookmark, it creates several subject proxies in the subject map where those objects don't already exist. Tagomizer is a kind of TMA (topic maps application -- or SMA in the newspeak of the TMRM), so it is responsible for identification of its subjects, some of which might already have subject identity granted by other TMAs. What, then, is a subject? Consider the webpage itself. Tagomizer asks the core TMA to create a subject proxy for a webpage with a given URL. If that subject proxy already exists, it is returned. Otherwise, a new one is created and granted subject identity by way of a PSI associated with the core TMA. Tagomizer, as a different TMA then grants that subject proxy subject identity with a different PSI, one that says "this is a subject identified by Tagomizer." Other TMAs might grant an SIP (psi) of their own. This is necessary because each individual TMA will be adding other properties to the proxy, mostly assertions.

So, a webpage has granted to it subject identity. What is the subject? In this case, subject identity has been granted to a particular resource, a webpage. Nothing more than that. The resource exists, it is located on the web at a particular URL, and it has been granted subject identity based on that URL by one or more TMAs. Each TMA is going to confer other properties on that subject. We know from nothing about the subject itself other than those properties of location and object type. What is contained/presented at that webpage will be the subject(s) of other subject proxies, for which that resource becomes an instance of an occurrence.

Brain pain, for me (warning: admission of ignorance forthcoming), stems from notions of essence. Essence is mentioned in the quote above as an intrinsic issue. Now, we're deep into the same issues that come up from time to time in the OODB community, intrinsic vs. extrinsic properties. There's an interesting thread on web resource identity, not dissimilar to Bernard's previous post on URI ambiguity. That xml-dev thread starts here.
Intrinsice-extrinsic properties are discussed here.

Closure? Is closure possible? I post this because I am interested in looking for concensus reality related to interoperable ways in which subject identity can/should be conferred on the subjects of future topic/subject maps. My sense is that the inquiry I reveal in this post represents the, um, essense of this entire blog and of Bernard's inquiry. I'll take my answers anywhere I can find them.

Pat Hayes on URI ambiguity

2006-01-27T11:34:00.000+01:00

In this excellent thread on SWBPD list, Pat Hayes makes a good point again. URI are ambiguous identifiers, and can be used for more than one referent, hence bearing different or conflicting semantics in different declaration or processing contexts. Just as any name.
Now, what I pushed lately here and there is that different URIs can have the same referent, but describe it differently from different perspectives. Hubjects are formalizations of referents as binding blank nodes. Those two points seem dual and complementary.
Where I differ with Pat is when he says that context, which indeed provides disambiguation of the referent, and is implicitly defined by rules of a given community, a given protocol, should stay this way. In other words, it can't, or should not, be formalized as an object, jusque like in ordinary conversation : the context is effective without being explicit. I think context (or perspective) could and should be declared formally ...

The Wheel and the Hub (six months later)

2005-12-27T12:47:00.000+01:00

Six months have passed since the first release of 'The Wheel and the Hub'. Thought it was time to revisit it, and make it consistent with a parallel new release of SPEK vocabulary. The new presentation is much shorter and more full of emptiness. Eventually I've came back to the first impression about it, which is well known to often turn out to be the best one. Blank Nodes are indeed the clue for representation of subjects, but with a subtle and important difference with the first version. Blank nodes representing subjects must be really empty, they have to bear absolutely no declaration of any property whatsoever, not even links to their various descriptions (as they did in the previous versions). It's up to the various descriptions to point to the same blank node, as so many fingers pointing at the Moon, and not the other way round ...
Following this logic, SPEK vocabulary has also be simplified to the extreme ... I don't need "views" and "aspects" any more. Any RDF description is a view and provides a specific aspect. Note also that 'hubject' is back in the SPEK vocabulary, but no more as a class, but as the property linking a description to the binding blank node.

I guess this is now as simple as possible ...

Forging URI schemes : best or bad practice?

2005-12-09T09:48:00.000+01:00

I've posted already about International Virtual Observatory Alliance. It has a forum called IVOA semantics. Current thread is about relevancy of forging new URI schemes, fit for a large community of users (like astronomers) vs http URLs.

The year of the unique ID

2005-12-09T09:37:00.000+01:00

Jack forwarded that one. JOHO stands for "Journal of Hyperlinked Organization". Food for thought based on the ISBN case. What does isbn:foo identifies?

Work (e.g., Hamlet)
Expression (e.g., the Folger's Hamlet with annotations and introduction)
Manifestation (a particular print run of Folger's Hamlet)
Item (a copy of Folger's Hamlet sitting on a shelf)

Work, expression, manifestation, item : four aspects, in four different perspectives, of the same hubject isbn:foo

Tom Gruber on Tag Identity

2005-11-25T10:37:00.000+01:00

Tom Gruber is famous for his striking and sensible aphorisms about ontologies such as "Every Ontology is a Treaty". He strikes again with this paper proposing an Ontology of Folksonomy.
In section 5, just before the conclusion, a bunch of questions about Tag Identity, showing that both Tags and URIs meet similar identification issues, in fact common to any naming mechanism, and neither is providing killing answers.

Identity, Reference and the Web

2005-11-21T19:26:00.000+01:00

A challenging workshop to be held in Edinburgh in May 2006. I've been invited today by the co-chair Harry Halpin to participate in the Program Committee. From the "Goal and Theme" section of the description.

URIs are the primary mechanism for reference and identity on the Web. To be useful, a URI must provide access to information which is sufficient to enable someone or something to uniquely identify a particular thing and the thing identified might vary between contexts. There is no doubt that as mechanisms for identifying web pages the URI has been wildly successful. Currently, URIs can also be used to identify namespaces, ontologies, and almost anything. However, important questions are the interpretation and use and meaning of URIs have been left unquestioned ...

Exactly indeed, what we are about here ... Interesting to see also Pat Hayes in the co-chairs list. I remember that quite a while ago in a private communication, Pat had stressed the fact that identity issues had been "sadly overlooked" so far by current Semantic Web technologies.

Compact URIs : The CURIE syntax

2005-11-21T18:50:00.000+01:00

I've started using this compact syntax in a project using IPTC specifications. Beyond the practical aspects well presented in the W3C note, it strikes me that CURIEs are good candidate hubject identifiers. For example ISBN:0201749602 is a compact URI which can be expanded automatically by various systems in so many URIs providing different views of the book, such as ...

New SPEK release

2005-11-21T17:47:00.000+01:00

Although previous release had not yield much feedback so far, I've kept hitting this nail of views, aspects and perspectives and eventually produced a new version of SPEK vocabulary. The new release is as simple as can be, although the RDF schema is quite weird at some points. It introduces a spek:Description which is not formally defined as subclass of rdf:Description, but which looks really like it. RDF editors are variously happy with it. SWOOP beta 2.3 seems to yield the best results among all I tried.
Hubject is no more an explicit class in this version, because I've figured out that about any resource could be used as a hub. I've kept "spoke" as the property linking a view to the resource it describes, but changed the direction : the spoke is directed inward to the (hubject resource), not outward from the hub.
As an example, I picked the "Air Pollution" hubject as defined by Wikipedia, and four different views : a term in a glossary, a descriptor in a thesaurus, a category in a taxonomy, and a class in an ontology.

SKOS in Topic Maps

2005-10-25T16:59:00.000+02:00

I've mentioned here a while ago the new blog of Lars Marius Garshol. His last post is about using SKOS vocabulary in Topic Maps, and is presented as a long overdue school work. Well done.
Now the crucial question is maybe not how you can do it (something Lars Marius shows quite neatly as usual), but why one would want to do that. Adding a real world use case would be cool ...

As simple as possible ...

2005-10-25T09:44:00.000+02:00

Those days Planet RDF is buzzing with a bunch of interesting responses to Danny Ayers' provocative question about alternatives to the Semantic Web (if possible simpler than the original stuff). Getting rid of artificial complexity gathered around the basically so-simple RDF model is of course the main preoccupation, and of course, the lack of canonical serialization in XML is seen as a major obstacle to adoption. At SemEmergence, Seth Ladd is crying for it:

Please, W3C, create a standard RDF serialization that elevates RDF as a first class citizen of XML. Everyone else has a schema, why can't we?

Having passed (too much) time those days struggling with the yet-another-serialization syndrom in the latest versions of SWOOP and Protégé, I could not agree more. But waiting for such a (most unlikely) W3C delivery, alternatives solutions pop up and are worth looking at.
Phil Jones pushes the notion of SynWeb, which he defines as a web which doesn't need "key identifiers".

The difference is that the knowledge needed to give semantics to the data resides in the programs which do the combining, rather than in a schema which has been prepared earlier.

No absolute meaning of data, no absolute identifiers, semantics in the application context? Certainly close to our current ramblings on perspectives and aspects.

The simplest and most radical alternative to-date is certainly Phil Dawes' tagtriples, a simple text format for triple statements. Forget URIs, namespaces, XML and the like. Identification is local to a graph (an ordered collection of statements), as indicated in the Tagtriples Model and Semantics (don't run away, that is really as simple as can be).

All occurances [sic] of a particular symbol in a graph must denote the same meaning. [...] The same symbol used in different graphs may or may not denote the same meaning - it is up to the consumer of the information to interpret how the symbol/meanings correspond.

Introducing SPEK

2005-10-21T15:59:00.000+02:00

Follow-up of the previous post. I eventually delivered a first release of SPEK, an RDFS vocabulary leveraging SKOS to express perspectives, aspects and hubjects.
More to come ...

Perspectives and SKOS

2005-10-20T17:45:00.000+02:00

Just thought time was ripe to push hubjects and Michel Biezunski's perspectives in the SKOS forum. Watch this place ...

Subject classification with DITA and SKOS

2005-10-20T12:15:00.000+02:00

DITA (Darwin Information Typing Architecture) has been developed by IBM since 2001, and introduces itself as a "topic-oriented architecture". DITA has its own definition of a topic, which is a bit different, and in a sense more restrictive, than the one(s) found in Topic Maps.

A topic is a unit of information that describes a single task, concept, or reference item.

The new publication, really worth reading, comes with a challenging academic subtitle : "Managing formal subjects", hiding in fact a very pragmatic approach:

In a topic-oriented architecture such as DITA, content is authored in small, independent units that are assembled to provide help systems, books, courses, and other deliverables. Each unit of information answers a single question for a specific purpose. That is, each topic has specific, independent subject matter -- the very reason that these units of information are called topics.

The paper then expands very neatly on how SKOS can be used to declare what the subject of a topic is, claiming that "subject" here is to be understood in the same sense than in "Published Subject Indicator".

Placeopedia = Google Earth + Wikipedia

2005-10-17T10:01:00.000+02:00

You all waited for it, here it is : connecting the most amazing geographical interface Google Earth with the ever-growing Wikipedia. Go to Placeopedia, pick an article in Wikipedia, find the place of the thing on Google maps, and pinpoint it. And that's it. You got a cool Wikipedia + Google Earth subject indicator. Just added the Very Large Telecope and Parañal Observatory. Better choose the "satellite" view to see something in those places, though, and don't look for accomodations around, they are sparse ... After that, add Placeopedia data to Google Earth, and see new added objects in real time. Awesome!

The Search for the Perfect Language

2005-10-10T09:34:00.000+02:00

Started diving in this fascinating book by Umberto Eco last week-end. Discovered the French translation available in my local library. Really worth reading, to understand that what we are doing here and in many other places today is just another episode of a very long story. A quote among many, this one from Descartes in a letter to Marin Mersenne in 1629 (my own translation from French, hope it makes sense).

I take that such a language is possible, and that the science on which it depends can be found, by mean of which farmers could best grasp the truth of things than philosophers do today. But don't hope to ever see it in use; that would suppose great changes in the order of things, and would need the world to be a heaven on earth, something worth to propose only in the world of novels.

Topic Maps for Libraries Wiki

2005-10-06T23:52:00.000+02:00

Announced by Suellen on Topic Maps list. Wiki Home quote :

Elaine Svenonius in her book The Intellectual Foundations of Information Organization states that the purpose of information organization is "to bring essentially like information together and to differentiate what is not exactly alike".

Suellen has also established a Topic Maps Interest Group within LITA (Library & Information Technology Association). I hope she will take the time to comment a little more about it here.

Lars Marius is alive and blogging at TMRA'05

2005-10-06T20:02:00.000+02:00

If you wonder where Topic Maps folks are today, you will find some of them, including Jack making the keynote, in Leipzig at TMRA'05. Lars Marius Garshol is there of course, and seems to have fun feeding his brand new blog, which is called simply "Larsblog" because he's a guy who loves simplicity. But I'll suggest him a more sexy name.
What about "Beer, Topic Maps and Everything."?

Anti-SPAM measures for comments

2005-10-03T12:49:00.000+02:00

We've started for a month or so to get a few SPAM attacks on universimmedia, in the form of random comments linking to a variety of sites generaly having nothing to do with the post. I've suppressed them manually so far, but their number has increased those days, so I have enforced the word verification procedure which should stop comments generated by automatic SPAM software.
Sorry for the extra inconvenient in posting comments.

Revisiting Content Negotiation

2005-09-28T09:21:00.000+02:00

I attended yesterday a very interesting telecon of the SWBPD Vocabulary Management Task Force. The agenda was highly technical - define best practices on how to provide through its URI, both computable RDF description for computers and human-readable description for humans, of an RDF vocabulary term. Use cases were SKOS and FOAF, with their respective editors Alistair Miles and Dan Brickley, and Dublin Core, represented by Tom Baker. All those smart guys have already explored the subject in-depth during recent Dublin Core Conference in Madrid, and agreed that current state of their respective vocabularies was suboptimal.
Devil is in the details there, for example many vocabularies use #URIs, such as http://www.w3.org/2004/02/skos/core#prefLabel.
From Topic Maps Published Subjects viewpoint, such an URI would be called a subject identifier, but in your browser, the fragid is not taken into account, because http://www.w3.org/2004/02/skos/core#prefLabel points to an RDF schema. So the subject identifier does not provide directly a human-readable HTML subject indicator, such as the one actually provided by http://www.w3.org/TR/swbp-skos-core-spec/#prefLabel
Everybody agreed that it would be good to have the subject identifier provide redirection to the subject indicator (even if this is not the terminology used so far in RDF land), at least for human users (that is, in a regular browser), whereas computers would keep being fed with the RDF description.
Consensus in this meeting was that content negotiation is the way to go. While it's unclear at this stage (at least for me) how it can be technically achieved, particularly with #URIs, it sheds a new light on Published Subjects specification, on which I expand in this post.
New thing here is that at the time of the specification (2003), we did not explore both possibilities offered and issues raised by content negotiation for Published Subjects.

Thinking further about it, it strikes me that content negotiation mechanism is very similar to hubjects. A URI managed through content negotiation is defining a subject/resource which is neither this content nor that one, but a superposition of all possible contents, the actual one being delivered in a given interaction depending of the client-server dialogue. It's amazing that impact of content negotiation on URI meaning seems to have been so much overlooked. Although the specification is now quite old, it seems to have been only used as a borderline technical trick, whereas it could become a fundamental mechanism to deliver, through the same URI, a variety of views of a subject to a variety of users, humans and computers as well.

Axioms of Identity

2005-09-21T19:34:00.000+02:00

Here is what Scott C. Lemon said:

In my research into digital identity, I created a set of 'axioms' that have molded my perspective of the subject. I developed these axioms as the foundation for how I would create a digital identity solution ... a software solution to accumulate identity, and provide controlled dissemination of that information.

The First Axiom of Identity

I posit that we humans do not have any inherent identity.

The Second Axiom of Identity

I posit that identity does not exist outside the context of a community.

The Third Axiom of Identity

I posit that identity is exchanged in transactions that occur within a context of trust and authentication.

nota bene: given the last update on these (4-3-2005), I'm guessing that Bernard didn't already mention them here earlier :)

Thinking about RDF and Topic Maps

2005-09-16T15:54:00.000+02:00

Danny Ayers, in this blog entry, talks about issues related to representations in RDF that speak to issues I have thought about for a while now. I think that now is a good time to start a dialog between the RDF tribe and the Topic Maps tribe. It's a double-edged knife, one that cuts both ways, looking at the true nature of the inquiries of each tribe.

I like to think about it this way: the core of the topic maps inquiry is to
satisfy a couple of important use cases: finding and reminding. In
those two use cases lie two primitive notions: subject identity and
names for things. Those are the two primitives that topic maps place
front and center, whereas, it seems to me, OWL emphasizes inferencing in
subsumption hierarchies, relegating subject identity to "proper use of URIs". I like to think about subject identity in the same terms a lawyer might do so in a court case. There, properties of the subject, more so than some URI, become all important. A trial might turn on something as trivial as shoes worn on some particular day. As topic maps are evolving, particularly in the case of the TMRM (topic maps reference model), we are seeing more emphasis placed on comparable subject properties than on precise URIs, which, in many cases, do not (yet) exist. We are seeing the evolution of the ability to "confer" identity on a subject according to circumstances. I think this line of inquiry can map directly into rdf work.

Topic maps (indeed, "subject maps") add one important consideration
outside subject identity and names for things: a guarantee that any
proxy for any subject (aka Topic), is the one place you need to go (in
*this* map) to find all that is knowable about that subject.

The knife cutting in the other direction suggests that, at the implementation level, topic maps could evolve along lines suggested from rdf work. Indeed, some of my own work involves the use of Jena coupled with JDBM for a backside.

GeoRSS

2005-09-14T09:45:00.000+02:00

GeoRSS is simple proposal for RSS feeds to also be described by location or Geotagged. It standardizes the way in which "where" is encoded with enough simplicity and descriptive power to satisfy most needs to describe the location of Web content.

This article further suggests to combine this geo-tagging with folkso-tagging, to provide pragmatic but efficient "what-where" identification.

Technorati Blog Finder

2005-09-06T13:54:00.000+02:00

Cool new (beta) feature on Technorati. I have added a profile for universimmedia, with a few tags such as this one or that one. Ideas for more relevant tags are welcome.

Semapedia

2005-09-06T12:19:00.000+02:00

Semapedia combines the physical annotation technology of Semacode with the availability of high quality information using the free encyclopedia Wikipedia.

Combination of 2D-barcode and bottom-up Published Subject Indicators. Bottleneck is that you need a physical reader on your mobile device, and have to find out physical tags. Next step is certainly to replace the semacode tags by RFID tags.

Simile Tools

2005-09-02T10:12:00.000+02:00

I've posted a few months ago about Piggy Bank, without clearly stating it is but one of the various tools developed by the Simile Project, Semantic Interoperability of Metadata and Information in unLike Environments. All RDF-based stuff, but user-friendly, a qualifier which does not come to mind when looking at some other RDF tools (no names, please). Have a look at Longwell browser, for example. You can try it on-line to find your way through W3C specifications. Local installation requires a bit of Java logistics, not tried it yet.
What people say about what they do is also interesting stuff. I had mentioned Stefano's Lynotype before. Posts are not frequent, but always thoughtful. See e.g. Data First vs. Structure first.

Vocabulary, taxonomy, thesaurus, ontology ...

2005-08-31T13:52:00.000+02:00

Still unclear about differences between those things? This is a neat and pragmatic introduction. The kind of stuff C*Os should be able to read and make sense of.
Seems that "Taxonomy" is the most trendy word those days, but if you take the time to make a bit of shopping at the Taxonomy Warehouse you will find all kinds of resources belonging to any of those types, and many more : subject headings, classification schemes, indexing schemes, reference models, dictionaries, glossaries ...

Google Sets

2005-08-31T10:24:00.000+02:00

Yet another Google tool. Sort of things clustering, results can be amazing.
Try {thing, subject, resource} or {Mondeca}.

No hierarchy revisited

2005-08-31T09:33:00.000+02:00

I've been re-discovering today this first exchange with Jack and others, about five years old now, amazed and quite pleased to find out we seem to keep following the same track, and to agree basically with most of what I wrote at the time. Don't know if that is supposed to be good news or bad news, though...
Actually there was an interesting notion introduced then that we have unfortunately a little forgotten since, which is subjects as attractors in conversations. This we should consider again, along with other mathematical tools linked to quantic superposition we have been discussing lately. On the same lines, I had an exchange a few days ago with Michel Biezunski who is currently exploring the field of fiber bundles as a possible tool for subject representation, in the line of his recent presentation at Extreme Markup 2005.

Blogos, the essence of your blog

2005-08-30T16:28:00.000+02:00

Being always quite eager to coin new words, and singularly through hybridation, such as hubject or semantopic, I'm just frustrated to have been beaten at that one. So what is the blogos of univers immedia?

Grafting , crossbreeding and other taxonomy breaches

2005-08-30T10:12:00.000+02:00

Follow-up of Jack's previous post. Biology has long ago set the rules for categorization, trying to capture the elusive but critical notions of taxon and species. Of course, it's always interesting to look at breaches in this system to see how robust it is. Without looking far away in the past to yet unclassified fossils, just consider common practices such as tree grafting and cattle cross-breeding. Interestingly enough, various religious traditions have been extremely touchy about them, often forbidding them merely because of entailed taxonomy breaches, the species organization being considered as the expression of some divine order. See for example this article showing how complex those issues can get in practice when addressed by Torah experts.
Most fears linked to bio-technologies are indeed to be considered at the same level. People are both fascinated and scared about hybrids and GM organisms, as they have always been about monsters and chimaeras of any kind, more for the breaches they make in their world representation than any objective danger they bring about.

Strange fossil defies grouping

2005-08-18T16:32:00.000+02:00

I've got to hand it to paleontologists. Go look at the artist's sketch of the creature that is the subject of the linked article, then look at the image of the creature itself. That someone can imagine such a creature from such a fossil is simply amazing. Nevertheless, there exists a creature that does not readly fit current models. The story gives rise to useful points about subject identity.

The trouble is the animal, named Vetustodermis planus, did not possess a set of features, or characters, which placed it clearly within any known group.

I am interpreting the word "characters" to mean characteristics. This creature identity issue is telling in the sense that it suggests open issues for topic maps subject identification processing. How does ISO 13250 address subject identification? Section 5.2.1 "Topic Link Architectual Form" of ISO 13250 suggests this:

The optional subject identity attribute refers to one or more indications ("subject descriptors") of the identity of the subject (the organizing principle) of the topic link.

There exist numerous interpretations of 5.2.1, which are manifest in XTM, TMDM, and TMRM. Is it appropriate to revisit the assumptions inherent in those interpretations?

I am indebted to Patrick Durusau for long and productive discussions centered around the subject identity issues related to topic maps implementations. I'd like to see such discussions in greater depth, in public.

Subject Identity: Now more than ever...

2005-08-16T16:13:00.000+02:00

Heard on the radio this morning while driving to work. Story about a woman who discovered that her 11-month old son was a terrorist. How could this be? A ticket agent at an airline prevented the child from boarding a flight. That's how. It seems that the given name of the child was found on the list of people to be prevented from boarding flights. It would seem that, in the context of merging topics in a topic map, it's dangerous to rely on names for things as a valid criteria.

More on Quantum Semantics

2005-08-10T14:53:00.000+02:00

Some follow-up of the previous post on Quantum Semantics ... While Justin Leavesley keeps hitting the nail in Semantic SuperPositions, I remembered an interesting presentation by Nikita Ogievetsky in Seattle Knowledge Technologies 2002 Conference about Quantum Topic Maps. Googling around for more, I stumbled on a bunch of interesting papers, introducing identification issues raised by Quantum Physics, and some logical or mathematical frameworks able to tackle them.

From the latter, in the conclusion :

We have suggested here that quantum objects are vague objects and, further, that how that vagueness is understood depends on the metaphysical package adopted with regard to their individuality. If quantum objects are taken to be individuals, as Lowe considers them, then the vagueness arises because of the existence of relations which do not supervene on monadic properties of the relata; it is because of such relations that we cannot tell which particle is which in an entangled state [...] The alternative package characterises quanta as non-individuals, where this is understood in terms of a lack of identity. [...] There are still some interesting questions to be addressed here, such as how it is that one can refer to objects for which one cannot even say that identity holds.

Is Information Science, at the dawn of 21st century, at a breaking point similar to the one crossed by Physics a century ago ?

Deep Web Research

2005-08-08T22:32:00.000+02:00

The link under the title points to an entity that is, on the surface, interesting:

DeepWebResearch.info is a Subject Tracer™ Information Blog developed and created by the Virtual Private Library™. It is designed to bring together the latest resources and sources on an ongoing basis from the Internet for deep web research which are listed below.

On the surface, it sounds like they are doing topic mapping of one sort of another. What is more interesting (to me) is how I landed on that site: mostly by way of a search for everything that is knowable about UIMA, IBM's Unstructured Information Management Architecture, which is being announced this week at LinuxWorld to go open source. It is already an Eclipse plugin. One of the search hits suggested that DeepWebResearch might be using UIMA in its technology.

Whether quantum mechanics, or category theory, or plain old propositional logic is at work, it is necessary that some form of information resource harvesting will be necessary. It seems a bit of great news that we can start pulling together a large array of available open source products to assemble ever more powerful harvesting tools.

Schrödinger's Web

2005-08-08T11:38:00.000+02:00

This is a follow-up of the previous post at Inbetween, providing yet more exciting thoughts about co-existence of many inconsistent descriptions of the same thing as a native feature of the Semantic Web.

It strikes me that if inconsistency is fundamental then it should be treated as such, not something to be avoided.

Follows the idea that maybe we need something like the logic of Quantum Physics for the Semantic Web. In such a framework, subjects would be seen, as quantic objects are, as superposition of mutually incompatible states, each one with a given probability. Pushing this concept further needs to define the notion of interaction. When you interact with a quantic object through an experiment, you get the very peculiar behavior known as wavefunction collapse in which the probability distribution changes suddenly in such a way that one particular state is actually "observed". Very long debates and crucial experiments eventually turned out to be rather in favor of the strictly probalistic interpretation, which some famous Quantum Physics founders (including Einstein) would not have been happy with.
I wonder if we are ready to go this far. Seems to me people will have hard time to, but eventually accept to live with the notion of subjects being by essence superposition of mutually inconsistent states, but going further to admit that observed properties of a subject in a given representation context are probabilistically determined would certainly prove at least as difficult as it has been in Physics. Took about a century there.
[Added] Thinking about it, the case certainly differs from Physics. The "semantic collapse" leading to specific representation properties is certainly not completely random, but rather likely to use some hidden variables depending on the representation context.

Perfect or sloppy - RDF, Shirky and Wittgenstein

2005-08-03T16:48:00.000+02:00

Danny Ayers picked this one up. Follows Clay Shirky's post on ontologies that I mentioned earlier. Here's the snippet that, I think, ties the linked subject to univers immedia:

It essential[ly] hinges on this, do you believe two people have ever in the history of humanity shared the same (i.e identical) concept. Do you believe that concepts exist as perfect entities that we share or infact do we say a concept is shared when we see a number of people using words in a similar enough way. i.e is the world fuzzz, sloppy and uncertain or is it perfect? Are concepts A Priori or derived?

Quoting further:

This is the essential error that Wittgenstein points out in his later work. There is no single shared meaning that we all can describe in our different ways. To believe so is to believe that a meaning exists A Priori and that language is just our means of describing it. Instead Wittgenstein turns it on its head and says, meaning is nothing more than the way a word is actually used by people.

The post then goes on to describe ways in which his comments are reflected in applications of RDF. Danny Ayers adds a comment to the post which says:

...the vast majority of software in use today is based on similar conceptual approximations, yet somehow manages to be useful.

What is a planet ?

2005-08-02T15:07:00.000+02:00

The debate has been around since Copernic and before ...

The claim Friday that a 10th planet has been discovered in our solar system has set off a fresh round of debate and international talks aimed at defining the most vexing term in astronomy: the word planet.

Bottom line : The more you know about a subject, the trickier it is to define.

Fun with Hubjects

2005-07-29T16:42:00.000+02:00

What happens when you are standing in the shower at oh-dark-thirty in the morning and you start thinking about hubjects? It goes like this.

A hubject is the result a phonetic accident when two memes, subject and hub, have a translocation error performed on them. This accident is part of what we now call directed evolution. By contrast, the philadelphia chromosome, known to be behind several cancers, the most prominent being chronic myelogenous leukemia, is a translocation error, not thought to be directed, between chromosomes 9 and 22. That error splices part of 9 with part of 22 into the famous BCR-ABL splice, characteristically referred to as "ph+" (because it was the first cancer gene discovered -- in Philadelphia -- following Watson&Crick). But, there remains the other parts which did not become famous, but which also get together. A dissertation at UCLA showed that object to be benign.

So, what's that got to do with hubjects? That's what hits when you've got soap in your eyes. In America, we have this whole thing about suburbs. Stay with me here; don't try to guess where this is going. We speak of living in the 'burbs. Could we say that a SubjectProxy (aka: Topic) living in a topic map is, um..., living in the 'bubs? Only if we had a different phonetic accident on the same memes and came up with, brace yourself, sububs.

You know, we can do that. Language is the longest running open source project in the entire universe. We can make up names for things till the cows come home, and beyond. At the core, however, the identity of the subject remains the same. Go figure.

We Are the Web

2005-07-29T10:27:00.000+02:00

Jack pointed this to me, certainly to temper the mood in my previous post. Not sure we wanted that, but certainly it's happening.

What will most surprise us is how dependent we will be on what the Machine knows - about us and about what we want to know. We already find it easier to Google something a second or third time rather than remember it ourselves. The more we teach this megacomputer, the more it will assume responsibility for our knowing. It will become our memory. Then it will become our identity. In 2015 many people, when divorced from the Machine, won't feel like themselves - as if they'd had a lobotomy.

Seeking sustainable IT (not yet desperately, but still ...)

2005-07-26T09:11:00.000+02:00

Underlying recent debates I've been involved here and there was a similar question : "Who cares about yet another language specification?". I found myself answering quite at the same time "Yes, please" on one side, and "No, thanks" on the other. And in this latter case, I was striken by a remark from Jim Mason - whose background in standard matters makes me always consider very carefully whatever he brings.

Let's face it. We're building these things for ourselves, and they're proliferating because we have fun doing it.

And any sofware vendor or consultant around could have added : " ... and because we hope to sell more technology build on top of it."
It made me wonder about the relevancy of some of the implicit assumptions which pushed me into Knowledge Engineering quite a while ago, and which I explicited at some point in a nutshell as : "Knowledge is sustainable information". Information is consumable and volatile, will be tomorrow at best redundant, at worst obsolete. By opposition, knowledge is supposed to be sustainable and building up with time. The more knowledge you have already gathered, the more you are likely to transform new information into more knowledge. So I envisioned "Knowledge Technologies" (KT) as another name for "Sustainable IT", along the lines of the European IST program spirit : "From Information Society to Knowledge Society". All of it was supported by my background, which made me consider Maths as the most impressive accumulation of (sustainable) knowledge ever, after natural languages of course.
Right opposite to this cumulative and patient build-up of knowledge we see in Maths and Science, proliferation of technology for the sake of it is clearly anything but sustainable. And actually, the current trend in which languages, software and hardware are all tied up in technological packages leads to this annoying conclusion that languages and specifications are bound to follow the same kind of "product life cycle" logic than their supporting software and harware. If Knowledge Technologies keep up following such a track, they clearly more belong to the technology-for-the-sake-of-it market logic than to sustainable knowledge building.
A very pernicious trend indeed, for many obvious reasons. Beyond the sheer issues of managing semantic interoperability between current, past and future languages and formats, lost of critical knowledge and data embedded in obsolete formats (see e.g. the Pionneer Anomaly), there are the human aspects of it : playing with a language is always more or less formatting your way of thinking. Dealing with too many different languages is difficult and confusing. Concepts are embedded in their representations, so considering language product life cycle means also considering concept life cycle. Not a very pleasant perspective.
I'm not sure what the requirements for sustainable IT would be. But surely one on them would be considering concepts the same way as life forms, with their needed diversity, fragility, and need for care.

Mission 2007

2005-07-22T10:12:00.000+02:00

This is maybe the most important KM project around. Objective is the creation of Knowlege Centers in each one of over 600,000 villages in India by 2007.
From the mission page :

What is now needed is the launching of a self-propelling, self-replicating and self-sustaining model of ICT for rural regeneration and prosperity [...] The term “knowledge center” was chosen because at the village level there is need for value addition to generic information by converting it into local-specific knowledge [...] The Mission will be top-down in its approach to technological connectivity, but bottom-up in relation to content and knowledge management.

Watch this space ...

News Metadata Framework Technical Specification

2005-07-08T16:26:00.000+02:00

News is a critical test-bed for identification and categorization issues. This draft delivered by the International Press Telecommunications Council is really worth a look.

What is a document?

2005-07-08T09:45:00.000+02:00

Just discovered the excellent Kevin Clarke's Worklog.
"What is a document" is a quite long and thoughtful entry (this blog is very verbose, many entries look like full papers), certainly relevant to recent debates about "information resource" vs "other resource", and more subtle than the recent resolution of httpRange-14 issue.

Ambiguity and imprecision

2005-07-01T16:55:00.000+02:00

I jumped on this thread on Forthcoming blog, after a similar exchange with TMRM folks on the same subject of ambiguity. It is deep down in the comments, so here is the quote.

I think there is two ways to consider ambiguity :
Way 1. Subjects are ill-defined, everything is fuzzy, nothing can be asserted for sure.
Way 2. Subjects are well defined, but in many ways, as so many views in/from different frameworks/perspectives.
Way 1 is good for unformal and cheerful conversation, like the one you used to have in forums, and now blogs, RSS, tagging and the like. But it is IMO pernicious : people either think they agree, though they speak passed each other, or the other way round think they disagree because they have no way to figure if they actually have different viewpoints, or if they speak about different things. Billions of examples available everyday.
Way 2 is what TMRM and hubjects are about : subjects are ambiguous, contradictory, fuzzy, moving targets, OK. But each view on a subject has better be well defined, and the rules for this definition explicit (perspective disclosed). You know your view is not exhausting the subject, you can explore different views, see if their logics are compatible, if they can play nicely with each other or are too orthogonal for that etc ... So you can agree that you agree or disagree on clear grounds, and go to war if needed, but with crystal clear reasons.

Meme tracker

2005-06-30T23:31:00.000+02:00

Before coining the term "hubject", I just made sure it was brand new, at least on the Web. All I got ten days ago with this query was some background noise due mainly to mispellings of "subject". Today you get a few hits, but if I judge by the very positive feedback I got so far it should spread. Before the public launch, I had pushed the term to Jack, and he sent me this page by Jon Udell on the O'Reilly Network, pointing to the final comment.

One of the advantages of coining a word is that you can track the progress of its associated meme. Last fall, in collaboration with readers of my blog, I settled on the word screencast. A couple of months ago it drew 200 Google hits, today the number is 60,000. Screencasting may never have the mainstream appeal of podcasting, a word coined not long before that now draws 8 million Google hits. But the meme is spreading and I can't wait to see where it goes next.

I can't wait either to see where hubjects go next, so I set this post as a permanent meme tracker. But so far, I can easily track myself the meme expansion. The last one to-date is freshly posted by Danny Ayers as Stuff of the Day, just after a quick mail "intercourse" triggered by Jack. Before that, I had a fruitful exchange with Patrick Durusau and Steve Newcomb, from which it appears that hubjects could be considered as no more no less than possible technical implementations of the "subject proxies" defined by the TMRM. Steve is even considering the introduction of hubjects in his Versavant implementation. Got also very positive feedback from Phil Tetlow, coordinator of the W3C SWBPD Software Engineering Task Force, already mentioned in those pages. More to come ...

The Wheel and the Hub

2005-06-28T16:42:00.001+02:00

Jack was asking for graphics. This is the best I could find to illustrate the metaphor in this latest version of my thoughts about hubjects. I like this image both for its sheer graphical quality, and for the fact that only the hub and spokes are visible. The wheel itself you can only guess.

Note : The Wheel and the Hub is now published under Mondeca namespace, including logo and copyright. The new URL is http://www.mondeca.com/content/download/455/3434/file/hubjects.pdf

Introducing Hubjects

2005-06-21T01:47:00.000+02:00

Hub + Subject = Hubject.

This paper is a rough first cut of an introduction
inspired by Chapter 11 of the Tao-te-King

Thirty spokes share the wheel's hub;
It is the center hole that makes it useful.

More to come, including examples and graphics.

httpRange-14 issue "Resolved"

2005-06-20T09:33:00.000+02:00

The W3C Technical Architecture Group announced on Saturday that the issue httpRange-14 was "resolved" (sic). Very weird resolution indeed, which links the kind of resource an http URI identifies ("information resource" or "any resource") to the type of answer to a GET request (2xx, 303 or 4xx). On the TAG list and on his blog Jan Algermissen wonders about the impact of such a decision, listing a few examples of application, and concluding with a good question indeed.

Question: Who is going to mint and maintain all the URIs to talk about dogs?

Ontology Definition Metamodel

2005-06-17T09:11:00.000+02:00

Certainly a major step towards semantic interoperability of Topic Maps, RDF, OWL, UML, Common Logic ... Really worth downloading and reading at length.

Blank Nodes continued

2005-06-16T23:33:00.000+02:00

Steve Newcomb took the time to make an excellent comment on my previous post. Actually, this comment would have deserved a full post, and I remind my old friend that he has a permanent invitation to appear here as a contributor, and I would be very honored if he could join. That said, Steve's viewpoint is much closer to mine that he seems to think.

SRN : I insist that subjects do have identity, but only within contexts -- within universes of discourse.

I did not write something very different when I wrote that only representations can have identity. Maybe I should have put it slightly differently, and I'm sure Steve will agree with this other way to put it : Whatever the subject, it has neither absolute identity, nor absolute definition, nor absolute property of any kind, that would be valid in any context. Identity, and all properties bound to this identity, is always conferred through a representation, itself defined inside the context of some representation scheme, and making sense only in the framework of this scheme.

SRN: But I don't see how it's meaningful to say that a proxy is not a proxy for something in particular. By its very nature, a proxy is always a proxy for something in particular.

Well here I think I disagree with Steve, if "something" is to be understood as "some thing". My view on this has always been that, for all practical reasons, it's the first act of "proxyfication" which brings the subject into existence, as a subject of conversation. But this debate is not really important, and we can proceed from here to the notion of subjects as blank nodes, with or without agreement on the separate existence of subjects. The original point of the debate set by Alistair and Dan was to know how to express in an efficient and meaningful way the fact that two or more representations in different schemes are somehow proxies for the same subject. My point was that this could be captured by something quite similar to an RDF blank node, lets' call it a Subject Blank Node, bearing no absolute identity, and of which only properties could be : represented this way here, and that way there.

The way I see it, a Subject Blank Node would have no logical property per se. It would not be part of any representation scheme, but would provide a hub between various schemes. Such a hub would allow applications able to make sense of several representations schemes, each with their specific structure and logical rules, to aggregate information from different schemes, such as a Topic in a TM application, a class in an OWL ontology, a concept in a SKOS scheme, a category in dmoz, a page in Wikipedia, a term in Wordnet, or a picture by Van Gogh, or a Nocturne of Chopin.

Ontology Mapping, Ineffable Subjects and Blank Nodes

2005-06-15T11:43:00.000+02:00

In this thread on SWAD forum, Alistair Miles and Dan Brickley re-activate an old issue : How do I express that resource X in representation scheme A (e.g. a SKOS concept scheme) and resource Y in representation scheme B (e.g. an OWL ontology) are somehow representations of the same (----) . After suggesting a suboptimal Topic Map solution I suddenly yesterday came out with the idea that in RDF, blank nodes could be a killer solution. Actually one can use blank nodes to aggregate various representations of whatever, keeping agnostic on what this whatever is. Using blank nodes to represent "ineffable subjects" is cool, since nobody is able to say anything directly about them (asserting name, type or any other property), since they have no URI. Put it together with recent debate on ISO SC34 mailing list about subject locators, and consider this provocative conclusion : RDF blank nodes are better than TM topics at representing subjects, since, and this is my last thought, subjects have no identity, only representations have one. Subjects have no identity, read no type, no property at all. Resources have identity (URIs), so the best attempt to indicate a subject is to gather various resources in a blank node, as so many fingers pointing towards the moon.
Remember in the Topic Maps book, I wrote about an empty subject indicator ...

Maybe ontologies aren't overrated after all...

2005-06-14T19:12:00.000+02:00

When Clay Shirky posted his now famous "Ontologies are overrated" paper, (see also here) a relatively new conversation started. Slipping in the sidelines, however, massive creativity continues. For instance, look at this page at del.icio.us where a small ontology of file types is used to refine the del.icio.us tags.

A comment to that post points to here, a page which enumerates things going on either for, around, or inspired by del.icio.us. One such link points to sid.vicio.us where a list of OWL ontologies exists, one of which is liberal.owl. rdf:about and rdf:resource attributes are links into del.icio.us content.

Bloom filters

2005-06-13T11:38:00.000+02:00

From Wikipedia:

The Bloom filter, conceived by Burton H. Bloom , is a space-efficient probabilistic data structure that is used to test whether or not an element is a member of a set. False positives are possible, but false negatives are not. Elements can be added to the set, but not removed (though this can be addressed with a counting filter). The more elements that are added to the set, the larger the probability of false positives.

A good list of papers about applications at the end of the article, including P2P networks. Certainly could be applied to automatic aggregation of Topic Maps too. To be compared with methods of Subject Identity Measure already mentioned.

Stumble Upon

2005-06-10T23:33:00.000+02:00

Stumbled upon this community tool yesterday. Quite amazing mix of FOAF and Bookmark sharing. I think Jack will love it, and become a stumbler too. The link on the side bar is to my personal stumble node.

Are "subject locators" bogus?

2005-06-10T12:37:00.000+02:00

Patrick Durusau, in the title post on Topic Maps ISO/IEC SC34 list, questions the notion of "subject locators" as defined by TMDM. His point is that through the network you never retrieve a resource, only some representation of it, depending on many things, including the global state of the client-server system at retrieval time, the state of the resource itself etc. Patrick quotes excerpts from the Thomas Fielding dissertation supporting such a view:

The early Web architecture defined URI as document identifiers. Authors were instructed to define identifiers in terms of a document's location on the network. Web protocols could then be used to retrieve that document. However, this definition proved to be unsatisfactory for a number of reasons ...

I tend more and more to agree with Patrick that this distinction TM make between "subject identifiers" and "subject locators", IOW between "subject indicator references" and "resource references" is certainly something to revisit. More on the thread ...