- From: Ian Horrocks <horrocks@cs.man.ac.uk>
- Date: Mon, 7 Apr 2003 18:19:06 +0100
- To: Daniel Elenius <danel698@student.liu.se>
- Cc: www-rdf-logic@w3.org
On April 3, Daniel Elenius writes: > > In the DAML+OIL walkthru[1], I think the Adult and Senior classes should > have > > <daml:toClass > rdf:resource="http://www.daml.org/2001/03/daml+oil-ex-dt#over17"/> > > instead of > > <daml:hasClass > rdf:resource="http://www.daml.org/2001/03/daml+oil-ex-dt#over17"/> > > (and same with "over59" for Senior). > > It doesn't technically matter in this case, because age is defined as a > UniqueProperty, but "hasClass" makes it sound like they can have several > ages and one of them should be "over17/over59", and just sounds less > intuitive. Daniel, This only works if we can deduce that all Persons have an age. If we can't deduce that (and I don't believe we can in this case), then the two are not equivalent - if we were to go with your formulation, then persons with (provably) no age would be Adults (and Seniors). Because they are really partial functions, the basic rule with UniqueProperties is that saying hasClass C is the same as saying both hasClass C *and* toClass C, but saying toClass C is not equivalent to saying both toClass C and hasClass C (because the property could be undefined for some individuals). Ian > > ------------------------------------------------------ > [1] http://www.daml.org/2001/03/daml+oil-walkthru.html
Received on Monday, 7 April 2003 21:37:47 UTC