- From: pat hayes <phayes@ai.uwf.edu>
- Date: Sun, 19 Jan 2003 23:12:00 -0800
- To: Brian McBride <bwm@hplb.hpl.hp.com>
- Cc: pfps@research.bell-labs.com, w3c-rdfcore-wg@w3.org
>From PFPS: > >>In trying to make the OWL semantics correspond to the RDF semantics I came >>up with the following problems in RDF datatyping: >> >>1/ A datatype is an element of IR, because the RDF MT says that datatypes are >>denoted by URI references. However, rdf:XMLLiteral is said to be a datatype >> but rdf:XMLLiteral is a URI reference. Something is wrong here. Nothing is wrong here. "rdf:XMLLiteral" is a uriref, and it denotes rdf:XMLLiteral, a resource which is a datatype. Peter seems to be making a use/mention confusion. But in any case, IR *can* contain urirefs, eg one can quote a uriref as a string. >> >>2/ XSD-interpretations include in their datatypes the XML Schema datatypes >>that are problematic when removed from XML documents or have other >>problems. They might, but that is not our problem or our business. We are required by charter to integrate RDF with the XSD datatypes. >> XSD-interpretations also include, for example, the datatype >>named FOO, which is not defined as an XML datatype. I fail to follow this point. It seems to be false, insofar as I can understand it. >> >>3/ A datatype has to be more than is specified in the RDF MT. Except for >>XSD-interpretations, which explicitly mention the URI-reference to datatype >>relationship, there is no way of tying the intended URI-reference for a >>datatype to that datatype. We do not specify it, but that is not the same as saying that it cannot be done. Seems to me that it can be done simply by fiat: I can publish a document which simply asserts that the uriref http://www.coginst.uwf.edu/~phayes/myexample#octalinteger denotes the datatype consisting of the integers with octal lexical forms. Viola. I anticipate that agreed methods of formally specifying the denotations of Urirefs will emerge. But that is not our business. >> For example, if I have D containing a datatype >>for integers and a datatype for strings, there is no way to require that a >>particular URI reference, say ex:int, denotes the integer datatype. Who is to say whether or not there is no way to require a URIref to denote a datatype? The RDF MT does not specify how this is to be done, but there is no reason why it should. But it is not impossible for someone to specify this in any way they feel like doing. I do not think that this is, or should be, an issue we need to be concerned with: it is part of a much larger issue of attaching meanings to urirefs. >>It probably makes more sense to say that a datatype is a four-tuple, >>consisting of a URI reference, a lexical space, a value space, and a >>lexical-to-value mapping. We could do that, but since we say that they are triples and are denoted by urirefs, the two formulations seem to me to be essentially equivalent. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32501 (850)291 0667 cell phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes s.pam@ai.uwf.edu for spam
Received on Monday, 20 January 2003 12:51:16 UTC