- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Thu, 20 Sep 2001 04:37:59 +0100
- To: Pat Hayes <phayes@ai.uwf.edu>
- Cc: w3c-rdfcore-wg@w3.org
At 03:58 PM 9/19/01 -0500, Pat Hayes wrote: >THIS is the case I originally had in there but decided to remove. It is >the analogous inference for domains: > >aaa rdf:domain zzz . >zzz rdfs:subClassOf yyy > >??entails?? > >aaa rdf:domain yyy > >and similarly for rdf:range, of course. My intuition is that this is not really helpful. I think the use of rdf:domain (etc.) comes from situations like this: aaa rdf:domain zzz . ppp aaa qqq . entails: ppp rdf:type zzz . which, together with with zzz rdfs:subClassOf yyy entails ppp rdf:type yyy . which I think is the "useful" conclusion one might draw from: aaa rdf:domain yyy . It's not clear to me that being able to deduce superclass domains really provides any useful information, and might increase the workload of an inference engine. This view is reinforced by the following consideration. A review of the schema-closure rules shows that the only triple one can generate from an rdfs:domain statement is an rdf:type statement. The above demonstration suggests that deducing superclass domains doesn't allow one to deduce any rdf:type statements that were not already available. In summary, I think, in the absence of specific contrary requirements, to stick with 'if' rather than 'iff' for the domain (and range) conditions. #g ------------------------------------------------------------ Graham Klyne MIMEsweeper Group Strategic Research <http://www.mimesweeper.com> <Graham.Klyne@MIMEsweeper.com> ------------------------------------------------------------
Received on Thursday, 20 September 2001 01:22:02 UTC