Ivan's Blog

Elie Sanchez was nice enough to send me a copy of the book he edited on fuzzy logic and Semantic Web[1]. Lots of stuff there which are not easy to digest for the non-initiated (and I am not one of those either…). But it is interesting to have a look at it nevertheless. Incorporating fuzziness into the Semantic Web world has been an issue for a while; I have received a number of comments from application developers that such functionality is really necessary to describe their knowledge base. (A relationship between two biological experimental results, for example, can rarely be stated with absolute certainty…).

The book includes several papers that extend the traditional DL with fuzzy statements. In one of the models one can state, for example:

<a:C ≥ 0.6>

meaning that "a" is of class "C" “on a 0.6 degree” . The interesting thing is that U. Straccia gives a full definition of SHOIN(D)’s fuzzy version (SHOIN(D) is the DL variant for OWL). However, as he says, there is no calculus yet for checking the satisfiability of fuzzy SHOIN(D). Of course, this is not the first time these issues are looked at. There was a workshop at last year’s ISWC[2] which addressed similar issues but, somehow, went largely unnoticed; I have not seen any reference to those papers in [1] although, for example, Stoilios et al. reported on a fuzzy version of a (weaker) DL dialect already[3] at that workshop. Oh well…

All papers I saw on the subject in [1] look at fuzziness on an ontology level. I was also looking for something like that on a lower level, ie, have the possibility of adding fuzziness on the RDF level already. Indeed, one should try to keep it simpler and use ontologies only when one really needs it… There is a paper in [2] from Mazzieri and Dragonidoing just that[4]. In their structure one can add a fuzziness on a triple level, ie:

n: s p o.

means that the (s p o) relationship holds on a degree of ≥n. The nice thing in [1] is that all the notions of RDF and RDFS can be translated to this setting, with a reasonable alternative definition of the whole model theoretical semantics of RDFS. They even report to have implemented a forward chaining fuzzy RDFS reasoner in Sesame… Of course the picture would really be complete if this could be expressed in SPARQL, too, but that may not be so complicated. (Hm. That may not be true. It seems that the current model theoretic semantics used in the latest version of SPARQL leads to a number of problems, so a fuzzy semantics might make it much worse. Let us have SPARQL finished first before going there…)

Nice things to think about; it is still to be seen whether this approach will solve real world problems. But it is worth investigating. Looking for a PhD topic? 

(B.t.w.: there will be a similar workshop at ISWC this year. I say similar: probabilistic reasoning and fuzzy logic, though attacking similar problems, are two distinct camps, and the practioners of both fields are very sensitive not to be mixed up with the other…

References

1. “Fuzzy logic and the Semantic Web”, E. Sanchez (ed.), Elsevier, 2006
2. Workshop on Uncertainty Reasoning for the Semantic Web, International Semantic Web Conference, eds, P. Costa, K. Laskey, K. Laskey, M. Pool, 2005. The full proceedings is also available on-line.
3. “A Fuzzy Description Logic f-SHIN’’, Giorgos Stoilos, Giorgos Stamou, Vassilis Tzouvaras, Jeff Pan, Ian Horrocks, in [2].
4. “A Fuzzy Semantics for Semantic Web Languages”, Mauro Mazzieri, Aldo Franco Dragoni, in [2].

I tried to get a reliable number, but it is not that easy…

The obvious starting point was Amazon. By simply searching through Amazon.com (using the key "semantic web") I got 165 hits. By doing the same via Amazon.uk I got 83 hits; this is not that surprising, the subsidiaries of Amazon have often less books. I then tried A9 (you can set A9 to search only for books, which is pretty cool), and I got a surprisingly high number: 1,495(!) hits. Of course, not all hits are valid, we all know that. I made therefore a cursory look at the A9 hits, just looking at the titles and (when available) the few extract linked from the search result page; my feeling is that the first 10 pages, ie, around 100 titles are relevant. These hits include conference or workshop proceedings, but also textbooks published by O’Reilly, MIT Press, Cambridge University Press, Springer Verlag, … I am sure by using other search engines the numbers would be different but probably not significantly.

I must admit that this number is higher than I expected. And the real number is actually even higher, because these hits refer to English titles only. A quick search through the German and French sites of Amazon brought forward a decent number of books in German, a book in French; I also know about books in Hungarian, there are no doubt books in Spanish, Italian, … I think the community is doing well in this respect!

By the way, Nova Spivack maintains a list on Amazon. There are relatively new items on the list, too, so it is probably up-to-date, which is good…

I had, for a long time, a small Python script to extract RDF/XML information from jpg files when that information has been put there by, eg, Adobe’s XMP. Typical example is when one uses the “file info” facility of Adobe Photoshop from Adobe CS or Adobe CS2. The script simply uses a regular expression matching to extract the information, nothing fancy.

I have now made an on-line version of this: one can use URI GET to extract the RDF content on any jpg file via its URI. Here is the example URI to use:

http://www.ivan-herman.net/cgi-bin/xmp.py?uri=http://www.ivan-herman.net/Photos/xmptest.jpg

If no RDF information is found in the file, an empty RDF/XML file is returned. It is one single Python file, you can copy it and install it on another server if you want.

Caveat: I originally intended to use this to access the metadata of my own photos when posted on my Web site. Unfortunately, the tool I use to generate the HTML pages, thumbnails, and the reduced size of the photos themselves does not copy the RDF (ie, XMP) content to the generated file . Ie, my photos on the Web do not contain this metadata. Oh well, maybe somebody else will find this script useful…

(I am almost sure there will be bugs in the script. Mail me then…)

Some of you may have already realized this, actually…

The home pages of the (now defunct) RDF Core and Web Ontology Working Groups used to include lists of development tools, programming environments, as well as references to commercial products. Clearly, maintaining such lists is difficult and, mainly, there is always a danger to become out of date (which is, actually, a good thing: it shows the good health of the Semantic Web related R&D…).

These lists have now been merged, updated, enriched with other references, and moved to the ESW Wiki of W3C. By doing that, we can hope that the community at large can maintain this list together, thereby keeping it as up-to-date and complete as possible. As I said: some of you may have already realized this, because updates have already been done in the past few weeks!

(For those of you who read this as a text-only RSS file, here is the URI: http://esw.w3.org/topic/SemanticWebTools.)

Something quite tragic happened a few weeks ago in the Netherlands, that makes one think about the limits of one’s own work…

There is a series typical Dutch events, called “vierdagse”, which are long walks in the countryside four days in a row. Different cities or villages organize it locally in spring or summer. It is an organized route involving a local organizing committee; a bit like the New York or Boston marathons, except that it is a day long walking instead of running, with four day in a row, and without the element of competion. There is no winner; just be there.

Nijmegen, one of the cities in the South-East of the Netherlands, organized this a few weeks ago. The problem was that it took place in the biggest heat-waves in the Netherlands for very very long time. Temperatures way over 30 degrees Centigrade, no wind, clear sky with blazing sunshine… At the end of the first day, 2 people died of heatstroke.

The remaining three days were called off, of course, but an inquiry was also set up to see if this was predictable by the local organizing committee or not. The person representing the organizing committee was interviewed on TV, and he said that they were careful in trying to predict the dangers, so they also consulted all the available Web sites on wheather predictions, and they decided that it should be o.k. They did not realize through the Web sites that there would be absolutely no wind at all (something very unusual in the Netherlands!), ie, no cooling effect in the afternoon through some breeze. This oversight proved to be fatal. However, (responding to a question to the interview) the organizing committee had not thought of contacting the real experts (ie, the local meteorological institute) directly. “The information on the Web was considered to be enough”.

This tragic story shows one problems that we, people working on Web technologies, should be aware of the Web’s limits as well as social dangers. How can one be sure that the information out there is right or, more to the point in this case, provides a full picture? This is clearly a partially technical but partially social issue. More technical work, but also more outreach, better explanation, a better management of the (social) expectations should be around…