From: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>

Date: Wed, 26 Jun 2002 22:38:14 +0200

To: las@olin.edu

Cc: Dan Connolly <connolly@w3.org>, pat hayes <phayes@ai.uwf.edu>, www-webont-wg@w3.org

Message-ID: <OF57C7C0D5.BB551C67-ONC1256BE4.006D4539@agfa.be>

Date: Wed, 26 Jun 2002 22:38:14 +0200

To: las@olin.edu

Cc: Dan Connolly <connolly@w3.org>, pat hayes <phayes@ai.uwf.edu>, www-webont-wg@w3.org

Message-ID: <OF57C7C0D5.BB551C67-ONC1256BE4.006D4539@agfa.be>

[...] > from > classExists :a > and > classEexists :b > 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) OK, got that > After all, if the classes :a and :b don't exist, what would the consequent > statement mean, anyway? well, :a and :b could be individuals, no? eg:LogicianClass owl:oneOf ( eg:LynnS eg:LynnS eg:PatH ) . [...] > 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....) Well, this is new... suppose classExists (eg:Number) then eg:LynnS would be a eg:Number ??? Anyhow, I've already dropped the rule { :rule9o1 . ?L owl:item ?x } log:implies { ?x a [ owl:oneOf ?L ] } . but we still have similar examples such as { :rule9u1 . ?L owl:item ?C . ?x a ?C } log:implies { ?x a [ owl:unionOf ?L ] } . The only way I know (so far) to rewrite rules with existentials in consequents is by using Skolem functions ala f(?x,?L) but it was exactly my point to interpret [ owl:OneOf ?L ] as a function *term* -- , Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/Received on Wednesday, 26 June 2002 16:39:01 UTC

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