- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Thu, 21 Nov 2002 08:34:03 -0500 (EST)
- To: jjc@hplb.hpl.hp.com
- Cc: www-webont-wg@w3.org
[It is hard to reply in-line to an HTML document. :-(] [...] > <h2><a name=3D"value">What is the value?</a></h2> > <p> > See > <a href=3D"http://www.w3.org/TR/rdf-concepts/#section-Literal-Value">RDF Concepts</a> > and/or > <a href=3D"http://www.w3.org/TR/2002/WD-rdf-mt-20021112/#dtype_interp">RDF Semantics</a>. > </p> > <p> > The value associated with a typed literal is found by applying the datatype > mapping associated with the datatype URI to the lexical form. > </p> Except for rdf:XMLLiteral. > <p>If the lexical form is not in the lexical space, then this is in error (semantically > but not syntactically). (The literal is not > well-formed). > The model theoretic treatment of errors is complicated (see below). Calling this an error is misleading, in my opinion. An invalid literal just denotes some junk value. [...] > <h2><a name=3D"webont">Webont specific issues</a></h2> > <p> > At least in the RDF world, the decision that literals are > resources makes the separation of datatyped and object properties harder. Somewhat harder, but not too much harder. > I believe this is a non-issue given the way OWL DL is defined. > I have produced an > <a href=3D"http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Nov/0055.html"> > awkward test case</a> based on there being only two boolean values > (Patrick Stickler summed up "Yes, I agree that the entailment holds. > No, I don't think it is very useful as a test case."). On the contrary, this is precisely the sort of thing that makes a useful test case. It is an entailment that can easily be missed by implementors. > The difficulty of defining new datatypes with URIs is a problem e.g. > <a href=3D"http://www.w3.org/TR/owl-guide/#Datatypes1">the wine year</a> > examples in the guide are nonstandard, and do not appear to be fixable. Well, I don't see why this is non-fixable. WebOnt could just state something like A datatype URI that is a fragment in an XML Schema document refers to the top-level simple datatype with that fragment as its local name, if any. [...] peter
Received on Thursday, 21 November 2002 08:35:30 UTC