- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Sat, 29 Jun 2002 00:06:23 -0400
- To: las@olin.edu
- Cc: connolly@w3.org, phayes@ai.uwf.edu, www-webont-wg@w3.org
From: "Lynn Andrea Stein" <lynn.stein@olin.edu> Subject: Re: TEST: Re: notes for 6/6 until 1:10 (oneOf/sameClassAs) Date: Wed, 26 Jun 2002 13:42:46 -0400 > > Stepping off a [BIG ;_)] cliff here.... > Text quoted in the following is excerpted from the full message at > http://lists.w3.org/Archives/Public/www-webont-wg/2002Jun/0183.html Context > is given only where it is necessary to understand what I'm saying, not why or > who said what's quoted. > > There were several examples in the cited email (and its predecessors) that I'd > like to propose restating with explicit assumptions about the implicit > existentials. I want to know whether the restatements are unacceptable. If > they are, then we may really have to deal with issues like > 5.10-DAML+OIL-semantics-is-too-weak, but if the restatements are acceptable > maybe they provide a way out. > > Example 1: > > >i.e. from nothing, conclude: > > > > > >[ owl:oneOf ( :a :a :b ) ] owl:sameClassAs [ owl:oneOf ( :b :a :a ) ] . > > Restatement: > > from > [owl:oneOf (:a :a :b)] the class owl:oneOf (:a :a :b) exists > and > [owl:oneOf (:b :a :a)] the class owl:oneOf (:b :a :a) exists > conclude > [ owl:oneOf ( :a :a :b ) ] owl:sameClassAs [ owl:oneOf ( :b :a :a ) ] . My view is that this begs the question entirely. I would think that everyone in the WG would agree with the above restatement. However, I view this restatement as a completely different example. > or even > > from > classExists :a > and > classEexists :b As already stated, :a and :b do not have to be (and were not thought of as) classes. > conclude > [ owl:oneOf ( :a :a :b ) ] owl:sameClassAs [ owl:oneOf ( :b :a :a ) ] . > > > (where classExists is just a shorthand for a statement that the class exists, > either using existing owl vocabulary or through some new mechanism) > > After all, if the classes :a and :b don't exist, what would the consequent > statement mean, anyway? Well, if :a and :b are in the vocabulary, then the consequent says that the two oneofs are the same. (Yes, the requirement that :a and :b be in the vocabulary may be missing.) > Example 2: > > ...the inference for (P and Q) from (Q and P)... in class > > language requires...: > > the existence of the class (P intersect Q) entails the existence > > of the class (Q intersect P). > > > Restatement: > > from > exists P, exists Q, Again, the requirement that P and Q are in the vocabulary might be missing. > (P and Q) Again, I view this condition as completely changing the example. > conclude > (Q and P) > > or > > from > classExists (P intersect Q) > conclude > classExists P > and > classExists Q > and > classExists (Q intersect P) Ditto. > Example 3: > > > (forall (?x ?L) > > (=> (ow:item ?L ?x) > > (exists (?ex1) (and (rdf:type ?x ?ex1) (owl:oneOf ?ex1 ?L))) ) ) > > Restatement: > pull the existential (as a special predicate) into the antecedent of the > implication, i.e. > > (forall (?x ?L ?ex1) > (=> (and (classExists (?ex1)) > (ow:item ?L ?x)) > (and (rdf:type ?x ?ex1) > (owl:oneOf ?ex1 ?L))) ) ) > > Again, if ?ex1 doesn't exist, then what on earth could the original statement > mean? (And the existence as a class of ?ex1 could be derived automatically > from the existence as a class of each of the elements in ?L....) The *whole* idea is that ?ex1 is forced to exist. Your change above either does nothing to the example or modifies it in the same unacceptable-to-me manner that you modified the previous examples. peter
Received on Saturday, 29 June 2002 00:06:35 UTC