- From: Pat Hayes <phayes@ihmc.us>
- Date: Sun, 14 Jan 2007 20:44:15 -0800
- To: Dan Brickley <danbri@asemantics.com>
- Cc: Jim Hendler <hendler@cs.umd.edu>, Kendall Clark <kendall@monkeyfist.com>, Uli Sattler <Ulrike.Sattler@manchester.ac.uk>, public-owl-dev@w3.org, Bijan Parsia <bparsia@cs.man.ac.uk>
>Pat Hayes wrote: >> >>>At 5:02 PM -0500 1/12/07, Kendall Clark wrote: >>>On Jan 12, 2007, at 1:15 PM, Jim Hendler wrote: >>> >>> I would like to see one "OWL Ultralite" that is as close to RDFS >>>as possible >>> >>> >>>I'd be happy to look at the model theory or axiomatization of such >>>a beast, if it's available. Not having seen anything yet, it's >>>hard to say whether it's interesting, either practically or >>>theoretically. >>> >>> >>> >>>Kendall - you've seen the model theory! This has been said all >>>along to be a subset of OWL, so the OWL documents provide the >>>model theory (and reference, and examples, and test cases, etc.) >>> >> >>Obviously (?) I would also be very interested in getting this >>right, also. But I think that rather than basing the model theory >>on OWL, the right way to do this is to follow the ideas developed >>by Herman ter Horst, who has written a lot on extending the RDFS >>style semantics. In particular, it ought to follow the RDF/S >>semantics in being non-extensional rather than the OWL insistence >>on extensionality: this gives a 'lighter' logic which is >>simultaneously more useful AND more tractable than a rigidly >>extensional logic. The pragmatic benefits of removing the >>extensionality condition have now been well validated (in a wider >>context) by the experience of using CL in the IKRIS project. >>Insisting that OWL be extensional was IMO a mistake, a good example >>of allowing theoretical 'elegance' to override useability >>considerations. >I'm intrigued. Are the IKRIS findings written up in detail anywhere? >Is http://www.ihmc.us/users/phayes/IKL/SPEC/SPEC.html a good place >to start? No, to start the best place would be the GUIDE, http://www.ihmc.us/users/phayes/IKL/guide/guide.html Appendix A is a long example all written as an IKL text. Also there are some slides and even a recorded talk about it on the Ontolog Wiki http://ontolog.cim3.net/cgi-bin/wiki.pl/ http://ontolog.cim3.net/file/resource/presentation/PatHayes_20061026/OntologyWorkshopSlides.html http://ontolog.cim3.net/file/resource/presentation/PatHayes_20061026/A-Logic-for-Ontology-Interoperation--PatHayes_AudioRecording-3464775-317865_20061026.mp3 BTW, what I didnt mention above is that since CL makes everything into a function and also a relation, this applies even to things like character strings and numbers. Which even I thought was slightly insane and was planning to write exceptions into the semantics to rule this out, until we discovered to our complete surprise that allowing strings to be functions was critical to providing a uniform way to describe opaque name usages. I feel even more certain that designing a logical language with as few syntactic restrictions as possible is a very important design principle. You really never know when one man's lunacy is another man's (or even the same man's, a little later) really neat idea. All the matters is that the semantics is coherent and the syntax is usable. Pat >cheers, > >Dan -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Monday, 15 January 2007 04:44:34 UTC