- From: pat hayes <phayes@ai.uwf.edu>
- Date: Tue, 25 Jun 2002 12:46:01 -0500
- To: Dan Connolly <connolly@w3.org>
- Cc: www-webont-wg@w3.org
>On Thu, 2002-06-06 at 17:31, Jos De_Roo wrote: >> >> [...] >> >> > 3d) Proposal to close issue 2.4 - Enumerated Classes (daml:oneOf) >> > issue: >[...] >> > Dan will reconsider a test case posted by Jos. >> >> that is actually the one in >> http://lists.w3.org/Archives/Public/www-webont-wg/2002May/0276.html >> "TEST: sameClassAs testcase" [1][2][3] > >i.e. from nothing, conclude: > >[ owl:oneOf ( :a :a :b ) ] owl:sameClassAs [ owl:oneOf ( :b :a :a ) ] . > > >Well, my position on 5.10-DAML+OIL-semantics-is-too-weak > http://lists.w3.org/Archives/Public/www-webont-wg/2002May/0235.html >is that OWL shouldn't entail the existence of any >classes from an empty premise. It would be useful to know what your basis is for taking this position. It seems to me to be unreasonable and arbitrary. For example, take the commutativity of conjunction, which when mapped into FOL is the inference for (P and Q) from (Q and P), which seems so blindingly obvious that it is hard to see how one could even formulate a sensible formalism that didnt support it, but in class language requires an inference of the kind you think should be ruled out: the existence of the class (P intersect Q) entails the existence of the class (Q intersect P). >i.e. there shouldn't be any axioms with existentials in >the conclusions. (there's a name for that fragment of FOL, no? >is that horn clauses? I often forget). Given that we are talking about Horn clauses (no disjunctions in conclusion), the subcase you are talking about seems to be that the sentences are universal, ie there are no existentials at all. (Existentials in the antecedent become universals over the whole rule.) >So I'm currently against rules such as: > { :rule9o1 . ?L owl:item ?x } log:implies { ?x a [ owl:oneOf ?L ] } . >from > http://www.agfa.com/w3c/euler/owl-rules I don't follow. That rule doesn't have an existential in the conclusion, does it? Both the variables in the conclusion are also in the antecedent. You seem to want to rule out any *terms* that refer to classes in the conclusion, not just existentials. That seems capricious to me. And the answer is, no, there isn't any logical name for that. 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, 25 June 2002 13:46:06 UTC