Thinking Clearly .

Description Logics underlie OWL DL (and OWL Lite, but OWL Lite is Mostly Pointless as a distinct category…another post will clarify), so it can be helpful to your OWL savviness have a better grip on the DL landscape. I hereby describe two of the more obscure useful resources. The first is maintained by my great friend, Uli Sattler, and is a list of current, actively maintained Description Logic reasoners. It’s interesting to note that 5 out of the 7 listed are explicitly targeted at OWL DL, and 3 (FaCT++, KAON2, and Pellet) mostly postdate the OWL recommendation. The revelation to me was the (somewhat impractical) MSPASS reasoner, which implements a decision procedure for the two-variable fragment of first order logic.

(I, stupidly, for the longest time, took the lack of a known goal directed decision procedure for SHOIQ to include the lack of a known decision procedure for the two variable fragment. Silly me.)

Evgeny Zolin maintains the amazingly cool Description Logic complexity navigator. Not only does it give you the (known) results on complexity for various Description Logics (described in terms of combinations of features), it also links to the relevant literature! So, for example, let’s do OWL Lite, which I happen to know is roughly the DL SHIF. So click on the F, I, S, and H buttons and voila, you now know all sorts of interesting facts. You can even find open problems (uncheck the I, for example).

One thing that would make this much better is if there were (persistent) URIs for each logic so I could link to them.

(I presume y’all know about Enrico Franconi’s DL course page, which is the best portal into the DL literature, at least for people trying to bootstrap.)

While it is mildly heartening that Republicans and conservatives are voicing concern at the blatant felonies of George W. Bush, it is sad that there was not equal concern over the crimes against humanity (torture and aggressive war). Similar to worrying about Clinton’s lying about sex rather than his genocidal sanctions policy against Iraq (although, Clinton’s minor offense seems much more minor, and wasn’t as systematic, whereas his body count is still higher, I believe).

This entry was posted on Monday, January 2nd, 2006 at 7:11 pm and is filed under Description Logic, OWL. 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.