From: pat hayes (phayes@ai.uwf.edu)
Date: 10/16/00
>[some of these questions/comments are starting >to make my brain hurt, Join the club :-) > but some of them are easy. >Rather than making the easy ones wait for the >hard answers, I'll answer in parts...] > >pat hayes wrote: > > > > >pat hayes wrote: > > > > > > > > In DAML-ONT: > > > > > > > > </Property> <Property ID="disjointUnionOf"> > > > > <label>disjointUnionOf</label> > > > > <domain resource="#Class"/> > > > > <range resource="#List"/> > > > > <comment> > > > > > > > > for unionOf(X, Y) read: X is the disjoint union of the classes in > > > > the list Y: (a) for any c1 and c2 in Y, disjointWith(c1, c2), > > > > and (b) i.e. if something is in any of the classes in Y, it's > > > > in X, and vice versa. > > > > > > > > cf OIL disjoint-covered > > > > </comment> > >[...] > > > > > <! QUESTION: what is the value of your disjoint-union when the > > >classes arent disjoint?> > > > > > >er... the same as the "value" of any other false assertion, > > >such as 5<4. > > > > Nah, but your disjoint-union isn't an assertion, its an operator. > >Yes, it is an assertion. > >In what way is > The class C is the disjoint union of the classes > in the list L. >not an assertion? > That is an assertion, but according to your specs "the disjoint union of the classes in the list L" has to be an assertion as well (since it can be false). What I meant was that the value of disjoint-union (or union or intersection etc) is normally taken to be a set, not a truthvalue. If the classes in L are pairwise disjoint then disjointUnion L is a set, but if they aren't it is false. (Now it is true that "The class C is false" is probably false as well, but that seems like a peculiar way to be false, and not what one would normally mean by saying that your assertion about C and L was false.) Pat Hayes --------------------------------------------------------------------- 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
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