Saturday, April 28, 2007

San Francisco and Challenges

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.

Friday, March 16, 2007


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: (Metaweb) and (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.

Monday, March 12, 2007

The benefit of Semantic MediaWiki

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 the 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.


Wednesday, February 28, 2007

DL riddle

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)

Friday, February 09, 2007

Talk in Korea

If you're around this Tuesday, February 13th, in Seoul, come by the Semantic Web 2.0 conference. I had the honor to be invited to give a talk on the Semantic Wikipedia (where a lot is happening right now, I will blog about this when I come back from Korea, and when the stuff gets fixed).

Looking forward to see you there!

Wednesday, February 07, 2007


The last two days my mail account had trouble. If you could not send something to me, sorry! Now it should work again.

Since it is hard to guess who tried to eMail me in the last two days (I guess three persons right), I hope to reach some this way.

Monday, February 05, 2007

Building knowledge together - extended

In case you did not notice yet -- the CKC2007 Workshop on Social and Collaborative Construction of Structured Knowledge at the WWW2007 got an extended deadline due to a number of requests. So, you have time to rework your submissions or finish yours! Also the demo submission deadline is upcoming. We want to have a shootout of the tools that have been created in the last few years, and get hands on to the differences, problems, and best ideas.

See you in Banff!

Tuesday, January 30, 2007

Collaborative Knowledge Construction

The deadline is upcoming! This weekend the deadline for submissions to the Workshop on Social and Collaborative Construction of Structured Knowledge at the WWW2007 will be over. And this may be easily the hottest topic of the year, I think: how do people construct knowledge in a community?

Ontologies are meant to be shared conceptualizations -- but how many tools really allow to build ontologies in a widely shared manner?

I am especially excited about the challenge that comes along with the workshop, to examine different tools, and to see how their perform. If you have a tool that fits here, write us.

So, I know you have thought a lot about the topic of collaboratively building knowledge -- write your thoughts down! Send them to us! Come to Banff! Submit to CKC2007!

Friday, January 12, 2007

Semantic MediaWiki goes business

... but not with the developers. Harry Chen writes about it, and several places copy the press release about Centiare. Actually, we didn't even know about it, and were a bit surprised to hear that news after our trip to India (which was very exciting, by the way). But that's OK, and actually, it's pretty exciting as well. I wish Centiare all the best! Here is their press release.

They write:
Centiare's founder, Karl Nagel, genuinely feels that the world is on the verge of an enormous breakthrough in MediaWiki applications. He says, "What Microsoft Office has been for the past 15 years, MediaWiki will be for the next fifteen." And Centiare will employ the most robust extension of that software, Semantic MediaWiki.
Wow -- I'd never claim that SMW is the most robust extension of MediaWiki -- there are so many of them, and most of them have a much easier time of being robust! But the view of MediaWiki taking the place of Office -- Intriguing. Although I'd put my bets rather on stuff like Google Docs (former Writely), and add some semantic spice to it. Collaborative knowledge construction will be the next big thing. Really big I mean. Oh, speaking about that, check out this WWW workshop on collaborative knowledge construction. Deadline is February 2nd, 2007.

Click here for more information about Centiare.

Saturday, December 30, 2006

Five things you don't know about me

Well, I don't think I have been tagged yet, but I could be within the next few days (the meme is spreading), and as I won't be here for a while, I decided to strike preemptively. If no one tags me, I assume to take one of danah's.

So, here we go:
  1. I was born without fingernails. They grew after a few weeks. But nevertheless, whenever they wanted to cut my nails when I was a kid, no one could do it alone -- I always panicked and needed to be held down.
  2. Last year, I contributed to four hardcover books. Only one of them was scientific. The rest were modules for Germany's most popular role playing game, The Dark Eye.
  3. I am a total optimist. OK, you knew that. But you did not know that I actually tend to forget everything bad. Even in songs, I noticed that I only remember the happy lines, and I forget the bad ones.
  4. I co-author a webcomic with my sister, the nutkidz. We don't manage to meet any schedule, but we do have a storyline. I use the characters quite often in my presentations, though.
  5. I still have an account with Ultima Online (although I play only three or four times a year), and I even have a CompuServe Classic account -- basically, because I like the chat software. I did not get rid of my old PC, because it still runs the old CompuServe Information Manager 3.0. I never figured out how to run IRC.
I bet no one of you knew all of this! Now, let's tag some people: Max, Valentin, Nick, Elias, Ralf. It's your turn.

Friday, December 29, 2006

Semantic Web patent

Tim Finin and Jim Hendler are asking about the earliest usage of the term Semantic Web. Tim Berners-Lee (who else?) spoke about the need of semantics in the web at the WWW 1994 plenary talk in Geneva, though the term Semantic Web does not appear there directly. Whatever. What rather surprised me, though, is, when surfing a bit for the term, I discovered that Amit Sheth, host of this year's ISWC, filed the patent on it, back in 2000: System and method for creating a Semantic Web. My guess would be, that is the oldest patent of it.

Thursday, December 14, 2006

Supporting disaster relief with semantics

Soenke Ziesche, who has worked on humanitarian projects for the United Nations for the last six years, wrote an article for on the use of semantic wikis in disaster relief operations. That is a great scenario I never thought about, and basically one of these scenarios I think of when I say in my talks: "I'll be surprised if we don't get surprised by how this will be used." Probably I would even go to state the following: if nothing unexpected happens with it, the technology was too specific.

Just the thought that semantic technology in general, and maybe even Semantic MediaWiki in particular, could relief the effects of a natural disaster, or maybe even safe a life, this thought is so incredible exciting and rewarding. Thank you so much Soenke!

Wednesday, December 13, 2006

All problems solved

Today I feel a lot like the nameless hero from the PhD comics, and what is currently happening to him (begin of the storyline, continuation, especially here, and very much like here, but pitily, not at all like here). Today we had Boris Motik visiting the AIFB, who is one of the brightest people on this planet. And he gave us a more than interesting talk on how to integrate OWL with relational databases. What especially interested me was his great work on constraints -- especially since I was working on similar issues, unit tests for ontologies, as I think constraints are crucial for evaluating ontologies.

But Boris just did it much cleaner, better, and more thorough. So, I will dive into his work and try to understand it to see, if there is anything left to do for me, or if I have to refocus. There's still much left, but I am afraid the most interesting part from a theoretic point is solved. Or rather, in the name of progress, I am happy it is solved. Let's get on with the next problem.

(I *know* it is my own fault)

Sunday, December 03, 2006

Semantic Wikipedia presentations

Last week on the Semantics 2006 Markus and I gave talks on the Semantic MediaWiki. I was happy to be invited to give one of the keynotes at the event. A lot of people were nice enough to come to me later to tell me how much they liked the talk. And I got a lot of requests for the slides. I decided to upload them, but wanted to clean them a bit. I am pretty sure that the slides are not self-sufficient -- they are tailored to my style of presentations a lot. But I added some comments to the slides, so maybe this will help you understand what I tried to say if you have not been in Vienna. Find the slides of the Semantics 2006 keynote on Semantic Wikipedia here. Careful, 25 MB.

But a few weeks ago I was at the KMi Podium for an invited talk there. The good thing is, they don't have just the slides, they also have a video of the talk, so this will help much more in understanding the slides. The talk at KMi has been a bit more technical and a lot shorter (different audiences, different talks). Have fun!

Saturday, November 18, 2006

Semantic MediaWiki 0.6: Timeline support, ask pages, et al.

It has been quite a while since the last release of Semantic MediaWiki, but there was enormous work going into it. Huge thanks to all contributors, especially Markus, who was written the bulk of the new code, reworked much of the existing, and pulled together the contributions from the other coders, and the Simile team for their great Timeline code that we reused. (I lost overview, because the last few weeks have seen some travels and a lot of work, especially ISWC2006 and the final review of the SEKT project I am working on. I will blog on SEKT more as soon as some further steps are done).

So, what's new in the second Beta-release of the Semantic MediaWiki? Besides about 2.7 tons of code fixes, usability and performance improvements, we also have a number of neat new features. I will outline just four of them:
  • Timeline support: you know SIMILE's Timeline tool? No? You should. It is like Google Maps for the fourth dimension. Take a look at the Timeline webpage to see some examples. Or at ontoworld's list of upcoming events. Yes, created dynamically out of the wiki data.
  • Ask pages: the simple semantic search was too simple, you think? Now we finally have a semantic search we dare not to call simple. Based on the existing Ask Inline Queries, and actually making them also fully functional, the ask pages allow to dynamically query the wiki knowledge base. No more sandbox article editing to get your questions answered. Go for the semantic search, and build your ask queries there. And all retrievable via GET. Yes, you can link to custom made queries from everywhere!
  • Service links: now all attributes can automatically link to further resources via the service links displayed in the fact box. Sounds abstract? It's not, it's rather a very powerful tool to weave the web tighter together: service links specify how to connect the attributes data to external services that use that data, for example, how to connect geographic coordinates with Yahoo maps, or ontologies with Swoogle, or movies with IMdb, or books with Amazon, or ... well, you can configure it yourself, so your imagination is the limit.
  • Full RDF export: some people don't like pulling the RDF together from many different pages. Well, go and get the whole RDF export here. There is now a maintenance script included which can be used via a cron job (or manually) to create an RDF dump of the whole data inside the wiki. This is really useful for smaller wikis, and external tools can just take that data and try to use it. By the way, if you have an external tool and reuse the data, we would be happy if you tell us. We are really looking forward to more examples of reuse of data from a Semantic MediaWiki installation!
I am looking much forward to December, when I can finally join Markus again with the coding and testing. Thank you so very much for your support, interest, critical and encouraging remarks with regards to Semantic MediaWiki. Grab the code, update your installation, or take the chance and switch your wiki to Semantic MediaWiki.

Just a remark: my preferred way to install both MediaWiki and Semantic MediaWiki is to pull it directly from the SVN instead of taking the releases. It's actually less work and helps you tremendously in keeping up to date.