Re: Fwd: problems with RDF datatyping

At 11:32 AM 1/17/03 +0000, Brian McBride wrote:

> 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.

I think we should say something like "rdf:XMLLiteral denotes a datatype".


>>2/ XSD-interpretations include in their datatypes the XML Schema datatypes
>>that are problematic when removed from XML documents or have other
>>problems.  XSD-interpretations also include, for example, the datatype
>>named FOO, which is not defined as an XML datatype.

Hmmm... I think we've understood in discussion that we don't expect *all* 
XSD datatypes to be recognized, but I'm not sure if the limitation here is 
adequately expressed anywhere.


>>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.  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.
>>
>>
>>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.

I'm not sure I fully understand this, but the final suggestion seems 
reasonable to me.

#g


-------------------
Graham Klyne
<GK@NineByNine.org>