- From: Sergey Melnik <melnik@db.stanford.edu>
- Date: Fri, 15 Feb 2002 09:35:18 -0800
- To: Pat Hayes <phayes@ai.uwf.edu>, Dan Connolly <connolly@w3.org>
- CC: RDFCore WG <w3c-rdfcore-wg@w3.org>, Dan Brickley <danbri@w3.org>
After the main telecon DanC raised the point of how S-B can still be used and how the lexical spaces of datatypes can be referred to. Pat suggested that writing xsd:date rdfs:range _:1 dc:Date rdfs:range _:1 could do the job of making the range of dc:Date to be the lexical space of xsd:date. I'm contesting this point and making a suggestion. As currently defined by the MT, the first statement asserts that image(IEXT(I(xsd:date))) is subset of CEXT(I(_:1)) That is, CEXT(I(_:1)) may contain many other things besides the lexical tokens for dates. What we would need, however, is CEXT(I(_:1)) is subset of image(IEXT(I(xsd:date))) i.e. a tighter restriction on the interpretation of _:1. Of course, we could define a new property like rdfs:restrictsByImage that has this effect. However, I think the most elegant way of handling this issue would be to introduce properties like rdfs:exactRange and rdfs:exactDomain with the "equals" semantics. For example, the interpretation for xsd:date rdfs:exactRange _:1 would be image(IEXT(I(xsd:date))) = CEXT(I(_:1)) In fact, these two properties are more powerful than rdfs:range and rdfs:domain or rdfs:restrictByImage altogether. For example, my:prop rdfs:exactRange _:1 _:1 rdfs:subClassOf my:Vehicle _:1 rdfs:subClassOf my:Boat achieves the same effect as my:prop rdfs:range my:Vehicle my:prop rdfs:range my:Boat I believe this is could be an issue for the schema subgroup (DanB?) to think about... Sergey
Received on Friday, 15 February 2002 12:04:51 UTC