- From: Dan Connolly <connolly@w3.org>
- Date: Wed, 27 Aug 2003 15:54:41 -0500
- To: Steven Gollery <sgollery@cadrc.calpoly.edu>
- Cc: www-rdf-logic@w3.org
On Wed, 2003-08-27 at 12:39, Steven Gollery wrote: > In DAML: > > if there is a property P1 whose domain is class C1 and range is class C2 I presume you mean to use domain/range in the sense of rdfs:domain and rdfs:range; i.e. C1 is *a* range of P1 and C2 is *a* range of P1. i.e. forall X, Y, if P1(X, Y) then X in C1 and Y in C2. and *not* the other fairly common usage of range, i.e. for all Y, if Y in C2 then there is some X with P1(X, Y). > and there is a property P2 whose domain is class C3 and range is class > C4 > and there is a statement that P1 is the samePropertyAs P2, > > does it follow that C1 is the sameClassAs C3 and C2 is the sameClassAs > C4, no. Counterexample: eats rdfs:domain Animal; rdfs:range Food.# P1/C1/C2 consumes rdfs:domain rdf:Resource; rdfs:range rdfs:Resource.# P2/C3/C4 Now we can have eats daml:samePropertyAs consumes. #i.e. same extension but lots of things can be in rdf:Resource without begin in Animal nor Food. > or does it just add a new class to the domain and range of each of > the properties? Umm... no, I don't think so; I'm not even sure what that means. > Or neither one? It just means that P1 and P2 have the same property extension. i.e. for every X and Y, P1(X,Y) iff P2(X,Y). fyi, the OWL equivalent of daml:samePropertyAs is owl:equivalentProperty. cf 4.2.1 owl:equivalentProperty http://www.w3.org/TR/2003/CR-owl-ref-20030818/#equivalentProperty-def and the links to the other parts of the specification that discuss equivalentProperty in Appendix C. OWL Quick Reference http://www.w3.org/TR/2003/CR-owl-ref-20030818/#appC -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 27 August 2003 16:54:53 UTC