- From: pat hayes <phayes@ai.uwf.edu>
- Date: Tue, 29 May 2001 10:05:09 -0500
- To: Dan Connolly <connolly@w3.org>
- Cc: www-rdf-logic@w3.org
> % hmm... are predicates > % limited to constants? > % The RDF 1.0 syntax suggests > % so, but n3 doesn't have that > % restriction It is conventional to so limit them, but we relaxed this in the new KIF without apparently causing enormous problems. When there are predicate variables it is difficult to prevent things like applying a predicate to itself (more generally, any 'loop' of applications, eg applying P to Q and Q to P) which breaks the 'standard' first-order model theory , but Chris Menzel invented a neat way to repair it without causing much harm, or one can be even braver and use a nonstandard set theory to do the semantics with. So in sum: go ahead and allow variables in predicate position, and if anyone accuses you of doing higher-order logic, send them to me. Pat --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
Received on Tuesday, 29 May 2001 11:05:17 UTC