Tuesday, February 08, 2005

I went to two PhD confirmation seminars at UQ today.

The first seminar was on defeasible logic. Interesting, but ultimately unsatisfying. This was because defeasible statements do not have a lot of applicability to RDF. It's not like we say, "Subject usually has Predicate on Object."

The second was about using Description Logics on RDF and OWL. Now this one seemed much more interesting from my perspective.

I was a little surprised about the scope of this second presentation. I can quote exactly which papers went into the seminar. I know exactly where the images were "lifted" from. I'm intimately familiar with almost everything presented.

The main difference with this project and my own was that it wanted to express a mathematical completeness for all of the DL used for OWL. As such, it dwelled for some time on TBox and ABox definitions, and their interactions. In fact, it did this so much that the question time at the end seemed to get bogged down in issues of how these relate to each other. I didn't expect this, as I was waiting to hear this all get tied back into OWL, but it didn't happen. It's like OWL was just the excuse for the motivation, rather than a real goal.

Other than the mathematical description of the logic, one purpose of this PhD was to create a working implementation based on the logic. However, I felt that there was not a lot of description on how this should be implemented. He talked about potential improvements over existing algorithms, but very little methodology. I'm keen to learn more about tableaux reasoners and the like so I can compare them to the rules engine I'd like to build, but this information was not there.

I also felt that the work was disturbingly parallel to my own. The issue that I have with this is that I'm only doing a Masters. What gives?

One thing that I'm thinking as a result of this seminar is that I should find a more formal way of describing the whole rules process. I can sort of describe individual steps, as these often come down to FOL, but I'm wondering if there is some way that the whole process can be described cleanly. I'd rather not work out how to do this for myself (if I can avoid it), so I should go looking to see if anyone has already done it. Guido is a rules expert, so perhaps I should ask him. OTOH, I'm likely to embarress myself if I'm asking something so fundamental. :-(

Anyway, I got in touch with Stone after he presented his seminar. He and I should be catching up over the next few days.

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