- From: patrick hayes <phayes@ai.uwf.edu>
- Date: Mon, 10 Jun 2002 15:01:22 -0400
- To: Dan Brickley <danbri@w3.org>
- Cc: w3c-rdfcore-wg@w3.org
>On Fri, 24 May 2002, Dan Brickley wrote: > <<snip>> > >We can note that: > >RDF provides a property rdfs:isDefinedBy that is a specialisation of the >rdfs:seeAlso property. This property is used to relate an RDF vocabulary >term (such a Class or Property) to the context within which it >is defined. Not unless we first say what 'is defined' means. Right now it seems to me that it doesn't mean anything, which is why the MT doesn't assign it any meaning. (Maybe it really does mean something, but we ought to make an effort to say what it is. ) BTW, is rdfs:isDefinedBy really required to be a subproperty of rdfs:seeAlso?? If so, I should put that in the RDFS closure rules. I have absolutely no idea what this subproperty assertion is supposed to be saying, so I cannot tell whether it is supposed to be true. >For every RDF property there is exactly one correct value for the >rdfs:isDefinedBy property. BUt that isnt expressible in RDFS. That is, two different urirefs might denote the same value, so 'unique value' doesn't cash out as 'unique URI'. Do you want it to be possible to infer from ex:foo rdfs:isDefinedBy ex:aaa . ex:foo rdfs:isDefinedBy ex:bbb . that ex:aaa and ex:bbb are equal? That would be a very creative way of introducing equality into RDF. >When RDF graphs are written in the RDF/XML 1.0 syntax, this value >corresponds to the XML namespace URIref used in the serialized >representation of the RDF properties. > >.... > >can we take this as a basis for progress? Not without a much clearer exposition of what it is talking about. > >The main clarification is that we represent explicitly the M+S claim that >there is just one schema for each property, But what does THAT mean? What is a 'schema' here? (People use this term a lot, but I have never seen it defined anywhere.) Do you mean there is at most one RDFS document that counts as the definition? If so, suppose the same term is used in another RDFS document, and I merge them. How does the part of the content that comes from the "definition" differ in meaning from the part that comes from somewhere else? If one graph contains a defined-by assertion, and the other graph uses that term, does the defined-by get incorporated into the merged graph? Does it then apply to the uses of the term that come from the document that DIDNT say refer to the definition? What happens if the two graphs being merged asserted different defined-bys? >and that rdfs:isDefinedBy >can thus be used to represent (within the RDF graph) the relationship that >holds between a property and the namespace within which it is defined. Again, I have no idea what this can mean. There is no notion of 'definition' in RDF, seems to me: its a purely assertional language. And are you identifying 'schema' with 'namespace'? Pat > >Dan > > >> - isDefinedBy is a Property >> - it has no further semantics in the RDF Model Theory >> >> - further sub-properties of it may be created by others >> - RDF Core doesn't currently expect to create any of these. -- --------------------------------------------------------------------- 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
Received on Monday, 10 June 2002 15:01:27 UTC