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Re: TEST: Re: notes for 6/6 until 1:10 (oneOf/sameClassAs)

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>

[...]

> 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 GMT

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