1. You ⊑ ∀need.Love (Lennon, 1967)
2. ⊥ ≣ compare.You (Nelson, 1985)
3. Cowboy ⊑ ∃sing.SadSadSong (Michaels, 1988)
4. ∀t : I ⊑ love.You (Parton, 1973)
5. ∄better.Time ⊓ ∄better­­­­­­­⁻¹.Time (Dickens, 1859)
6. {god} ⊑ Human ⊨ ? (Bazilian, 1995)
7. Bad(X)? (Jackson, 1987)
8. ⃟(You ⊑ save.I) (Gallagher, 1995)
9. Dreamer(i). ∃x : Dreamer(x) ∧ (x ≠ i). ⃟ ∃t: Dreamer(you). (Lennon, 1971)
10. Spoon ⊑ ⊥ (Wachowski, 1999)
11. ¬Cry ← ¬Woman (Marley, 1974)
12. ∄t (Poe, 1845)

Solutions: Turn around your monitor to read them.

Yihon Ding has an interesting blogpost taking analogies to the laws of thermodynamics and why this means trouble for the Semantic Web.

I disagree in one aspect: I think it is possible to invest the amount of human power to the system and to still keep it going. I can't nail it down exactly -- I didn't read "Programming the Universe" yet, so I can't really discuss it, but the feeling goes along the following lines: the value of a network increases superlinearly, if not even quadratic (Metcalfe's Law), whereas the amount of information increases sublinearly (due to redundancies in human knowledge). Or, put it in another way: get more people and Wikipedia or Linux gets better, because they have a constrained scope. The more you constrain the scope the more value is added by more people.

This is an oversimplification.

Now that the Cool URIs for the Semantic Web note by Richard and Leo have been published -- congratulation guys! -- I am sure looking forward if anyone will create a nice badge and a procedure to get official Certificates of Coolness. Pretty please?

On a different note: I know, I should have blogged from New Zealand. It sure was beautiful Maybe I will still blog about it a bit later. My sister has blogged extensively, and also made a few great pictures, take a look over there if you're interested.

Yes! Three weeks of vacation in New Zealand, which is rumoured to be quite a beauty. This also means: three weeks no work, no projects, no thesis, no Semantic We...

Oh, almost. Actually I will enjoy to have the opportunity to give a talk on Semantic Wikipedia while staying in Auckland. If you're around, you may want to come by.

It is on February 22nd, 1pm-2pm at the AUT. You may want to tell Dave Parry that you're coming, he is my host.

Looking forward to this trip a lot!

Obviously, the social web is coming. And it's also coming to this year's WWW conference in Beijing!

I find this topic very interesting. The SWKM picks up the theme of last year's very successful CKC2007 workshop, also at the WWW, where we aimed at allowing the collaborative knowledge construction. The SWKM is a bit broader, since it is not just about knowledge construction, but about the whole topic of knowledge management, and how the web changes everything.

If you are interested in the social web, or the semantic web, or specifically about the intersection of these two, and how it can be applied for knowledge management within or without an organisation, you will like the SWKM workshop at the WWW2008. You can submit papers until January 21st, 2008. All information can be found at the Social Web and Knowledge management workshop website.

After about two years of development and already with installations all over the world, we are very happy to announce the release of Version 1.0 of Semantic MediaWiki, and thus the first stable version. No alpha, no beta, it's out now, and we think you can use it productively. Markus managed to release it in 2007 (on the last day of the year), and it has moved far beyond what 0.7 was, in stability, features, and performance. The biggest change is a completely new ask syntax, much more powerful since it works much smoother with MediaWiki's other systems like the parser functions, and we keep constantly baffling ourselves about what is possible with the new system.

We have finally reached a point where we can say, OK, let's go for massive user testing. We want big and heavy used installations to test our system. We are fully aware that the full power of the queries can easily kill an installation, but there are many ways to tweak performance and expressivity. We are now highly interested in performance reports, and then moving towards our actual goal, Wikipedia.

A lot has changed. You can find a full list of changes in the release notes. And you can download and install Semantic MediaWiki form SourceForge. Spread the word!

There remains still a lot of things to do. We have plenty of ideas how to make it more useful, and our users and co-developers also seem to have plenty of ideas. It is great fun to see the numbers of contributors to the code increase, and also to see the mailing lists being very lively. Personally, I am very happy to see Semantic MediaWiki flourish as it does, and I am thankful to Markus for starting this year (or rather ending the last) with such a great step.

Time is running totally crazy on me in the last few weeks. Right now I am in San Francisco -- if you like to suggest a meeting, drop me a line.

The CKC Challenge is going on and well! If you didn't have the time yet, check it out! Everybody is speaking about how to foster communities for shared knowledge building, this challenge is actually doing it, and we hope to get some good numbers and figures out of it. An fun -- there is a mystery prize involved! Hope to see as many of you as possible at the CKC 2007 in a few days!

Yet another challenge with prizes is going on at Centiare. Believe it or not, you can actually make money with using a Semantic MediaWiki, wih the Centiare Prize 2007. Read more there.

I got the chance to get a close look at Freebase (thanks, Robert!). And I must say -- I'm impressed. Sure, the system is still not ready, and you notice small glitches happening here and there, but that's not what I was looking for. What I really wanted to understand is the idea behind the system, how it works -- and, since it was mentioned together with Semantic MediaWiki one or twice, I wanted to see how the systems compare.

So, now here are my first impressions. I will sure play more around with the system!

Freebase is a databse with a flexible schema and a very user friendly web front end. The data in the database is offered via an API, so that information from Freebase can be included in external applications. The web front end looks nice, is intuitive for simple things, and works for the not so simple things. In the background you basically have a huge graph, and the user surfs from node to node. Everything can be interconnected with named links, called properties. Individuals are called topics. Every topic can have a multitude of types: Arnold Schwarzenegger is of type politician, person, actor, and more. Every such type has a number of associated properties, that can either point to a value, another topic, or a compound value (that's their solution for n-ary relations, it's basically an intermediate node). So the type politician adds the party, the office, etc. to Arnold, actor adds movies, person adds the family relationships and dates of birth and death (I felt existentially challenged after I created my user page, the system created a page of me inside freebase, and there I had to deal with the system asking me for my date of death).

It is easy to see that types are crucial for the system to work. Are they the right types to be used? Do they cover the right things? Are they interconnected well? How do the types play together? A set of types and their properties form a domain, like actor, movie, director, etc. forming the domain "film", or album, track, musician, band forming the domain "music". A domain is being administrated by a group of users who care about that domain, and they decide on the properties and types. You can easily see ontology engineering par excellence going on here, done in a collaborative fashion.

Everyone can create new types, but in the beginning they belong to your personal domain. You may still use them as you like, and others as well. If your types, or your domain, turns out to be of interest, it may become promoted as being a common domain. Obviously, since they are still alpha, there is not yet too much experience with how this works out with the community, but time will tell.

Unsurprising I am also very happy that Metaweb's Jamie Taylor will give an invited talk at the CKC2007 workshop in Banff in May.

The API is based on JSON, and offers a powerful query language to get the knowledge you need out of Freebase. The description is so good that I bet it will find almost immediate uptake. That's one of the things the Semantic Web community, including myself, did not yet manage to do too well: selling it to the hackers. Look at this API description for how it is done! Reading it I wanted to start hacking right away. They also provide a few nice "featured" applications, like the Freebase movie game. I guess you can play it even without a freebase account. It's fun, and it shows how to reuse the knowledge from Freebase. And they did some good tutorial movies.

So, what are the differences to Semantic MediaWiki? Well, there are quite a lot. First, Semantic MediaWiki is totally open source, Metaweb, the system Freebase runs on, seems not to be. Well, if you ask me, Metaweb (also the name of the company) will probably want to sell MetaWeb to companies. And if you ask me again, these companies will make a great deal, because this may replace many current databases and many problems people have with them due to their rigid structure. So it may be a good idea to keep the source closed. On the web, since Freebase is free, only a tiny amount of users will care that the source of Metaweb is not free, anyway.

But now, on the content side: Semantic MediaWiki is a wiki that has some features to structure the wiki content with a flexible, collaboratively editable vocabulary. Metaweb is a database with a flexible, collaboratively editable schema. Semantic MediaWiki allows to extend the vocabulary easier than Metaweb (just type a new relation), Metaweb on the other hand enables a much easier instantiation of the schema because of its form based user interface and autocompletion. Metaweb is about structured data, even though the structure is flexible and changing. Semantic MediaWiki is about unstructured data, that can be enhanced with some structure between blobs of unstructured data, basically, text. Metaweb is actually much closer to a wiki like OntoWiki. Notice the name similarity of the domains: freebase.com (Metaweb) and 3ba.se (OntoWiki).

The query language that Metaweb brings along, MQL, seems to be almost exactly as powerful as the query language in Semantic MediaWiki. Our design has been driven by usability and scalability, and it seems that both arrived at basically the same conclusions. Just a funny coincidence? The query languages are both quite weaker than SPARQL.

One last difference is that Semantic MediaWiki is fully standards based. We export all data in RDF and OWL. Standard-compliant tools can simply load our data, and there are tons of tools who can work with it, and numerous libraries in dozens of programming languages. Metaweb? No standard. A completely new vocabulary, a completely new API, but beautifully described. But due to the many similarities to Semantic Web standards, I would be surprised if there wasn't a mapping to RDF/OWL even before Freebase goes fully public. For all who know Semantic Web or Semantic MediaWiki, I tried to create a little dictionary of Semantic Web terms.

All in all, I am looking forward to see Freebase fully deployed! This is the most exciting Web thingy 2007 until now, and after Yahoo! pipes, and that was a tough one to beat.

Comments are still missing on this post.

I can't comment on Tim O'Reilly's blog right now it seems, maybe my answer is too long, or it has too many links, or whatever. It only took some time, my mistake. He blogged about Semantic MediaWiki -- yaay! I'm a fanboy, really -- but he asks "but why hasn't this approach taken off? Because there's no immediate benefit to the user." So I wanted to answer that.

"About Semantic MediaWiki, you ask, "why hasn't this approach taken off?" Well, because we're still hacking :) But besides that, there is a growing number of pages who actually use our beta software, which we are very thankful to (because of all the great feedback). Take a look at discourseDB for example. Great work there!

You give the following answer to your question: "Because there's no immediate benefit". Actually, there is benefit inside the wiki: you can ask for the knowledge that you have made explicit within the wiki. So the idea is that you can make automatic tables like this list of Kings of Judah from the Bible wiki, or this list of upcoming conferences, including a nice timeline visualization. This is immediate benefit for wiki editors: they don't have to make pages like these examples (1, 2, 3, 4, 5, or any of these) by hand. Here's were we harness self-interest: wiki editors need to put in less work in order to achieve the same quality of information. Data needs to be entered only once. And as it is accessible to external scripts with standard tools, they can even write scripts to check the correctness or at some form of consistency of the data in the wiki, and they are able to aggregate the data within the wiki and display it in a nice way. We are using it very successfully for our internal knowledge management, where we can simply grab the data and redisplay it as needed. Basically, like a wiki with a bit more DB functionality.

I will refrain from comparing to Freebase, because I haven't seen it yet -- but from what I heard from Robet Cook it seems that we are partially complementary to it. I hope to see it soon :)"

Now, I am afraid since my feed's broken this message will not get picked up by PlanetRDF, and therefore no one will ever see it, darn! :( And it seems I can't use trackback. I really need to update to a real blogging software.

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Yesterday we stumbled upon quite a hard description logics problem. At least I think it is hard. The question was, why is this ontology unsatisfiable? Just six axioms. The ontology is availbe in OWL RDF/XML, in PDF (created with the owl tools), and here in Abstract Syntax.

Class(Rigid complete restriction(subclassof allValuesFrom(complementOf(AntiRigid))))
Class(NonRigid partial)
DisjointClasses(NonRigid Rigid)
ObjectProperty(subclassof Transitive)
Individual(publishedMaterial type(NonRigid))
Individual(issue type(Rigid) value(subclassof publishedMaterial))

So, the question is, why is this ontology unsatisfiable? It is even a minimally unsatisfiable subset, actually, that means, remove any of the axioms and you get a satisfiable ontology. Maybe you like to use it to test your students. Or yourself. The debugger in SWOOP actually gave me the right hint, but it didn't offer the full explanation. I figured it out, after a few minutes of hard thinking (so, now you know how bad I am at DL).

Do you know? (I'll post the answer in the comments if no one else does in a few days)

(Just in case you wonder, this ontology is based on a the OntOWLClean ontology from Chris Welty, see his paper at FOIS2006 if you like more info)

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