Thinking Clearly .

Boris Motik has completed his dissertation (and graduated and moved to his postdoc position at the University of Manchester):

Reasoning in Description Logics using Resolution and Deductive Databases

It is a notable achievement and a pretty damn good read. In it Boris…

• ...provides a novel, resolution-based decision procedure for very expressive description logics (like OWL) and shows that it is at least a reasonable alternative to standard tableau-based procedure. That is, an optimized reasoner (e.g., KAON2) built around his procedure can be competetive (overall) with existing optimized reasoners (e.g., Racer, Pellet, FaCT++, etc.). There are tradeoffs and KAON2 has not had the many years of development that Racer has, so there is a lot of room to explore. Also, I think there are insights to be gained for implementors of tablaeu-based reasoners.
• ...describes a new rule combination formalism, “DL Safe” rules, which is, I believe, the most expressive first order combination of DLs and rules currently known. He provides a decision procedure (based on resolution) and a number of interesting theoretical results, as well as a nice clean discussion.
• ...describes a decidable and useful metamodeling extension to very expressive description logics (like OWL), with an excellent discussion (his presentation at ISWC of his best-paper-winning version was exceptionally clear and accessible), and some useful theoretical results (ALC + OWL Full like metamodeling is undecidable).
• ...implements conjunctive query answering over DL/DL Safe knowledge bases which, for a variety of “shapes” of KBs is the best current implementation (by using deductive database techniques)
• ...proves several other nice theoretical results, including data complexity bounds for SHIQ
• ...defines a new subset of OWL, hornSHIQ, which is much more expressive than DLP.

Also, he has a number of insightful discussions along the way. There is a lot to learn from Boris in this work, and there will, no doubt, be lots to learn from him in the future.

Go read it.

The state of the union is one of lawlessness, torture sanctioning, aggressive war, leader worship, lies, incompetency, and corruption. I’m upset.

This entry was posted on Friday, February 3rd, 2006 at 10:38 pm and is filed under Description Logic, OWL, Rules. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.