At 00:45 10/04/04 -0400, Dan Brickley wrote: >Literal-valued properties, as well as URI-valued properties (and for >that matter, bNode-valued properties, if such scenarios can plausibly be >concocted). Seems easy enough: the person who wrote a book whose title is "Moby Dick" ? >Yes, I believe (in light of the 3-4 year FOAF experiment) that such a >disclaimer is appropriate. When we started FOAF there was no class >owl:InverseFunctionalProperty. Now we have it, but I am not 100% >convinced the semantics it has (due to the approach we took to >formalising RDF and OWL) capture entirely what we need for >reference-by-description. Specifically, OWL allows that the >property/value pair might match different individuals in different >interpretations, and guarantees "at most one"-ness only with regard to >a single interpretation. In FOAF, I say that properties such as >foaf:mbox and foaf:homepage are "Static inverse functional properties", >as a (not yet formalised) way of claiming that they cannot take >different values at different times. If you believe "a1 foaf:homepage >d2", you should not be prepared to believe a2 foaf:homepage d2" at a >later date. I don't believe these issues are fully explored yet, so am >wary of sending an "OWL solves this once and for all" message. Also, even within a single interpretation, it is common enough in real-world usage to depend on uniqueness of a combination of properties; e.g. The person whose name is ... who resides at ... whose date of birth is ... I'm not aware of an OWL construct that achieves this. (Or am I missing something?) #g ------------ Graham Klyne For email: http://www.ninebynine.org/#ContactReceived on Tuesday, 13 April 2004 07:04:26 GMT
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