- From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
- Date: Mon, 14 Nov 2011 16:18:32 +0100
- To: Richard Cyganiak <richard@cyganiak.de>
- CC: public-rdf-wg@w3.org
Le 10/11/2011 18:43, Richard Cyganiak a écrit : > Alex, > > On 10 Nov 2011, at 16:33, Alex Hall wrote: >> That's almost exactly what RDF Semantics 2004 says: "Typed literals whose type is not in the datatype map of the interpretation are treated as before, i.e. as denoting some unknown thing." (Section 5.1) > > Oh, I thought I carefully read all of Section 5 but had missed that sentence. That addresses the situation indeed. > > I note the following sentence: > > [[ > The condition does not require that the URI reference in the typed literal be the same as the associated URI reference of thedatatype; this allows semantic extensions which can express identity conditions on URI references to draw appropriate conclusions. > ]] I do not understand this phrasing. > > So if the graph contains "xxx"^^<not-a-datatype>, then the literal might still acquire a value because<not-a-datatype> might be owl:sameAs xsd:string, but not in any of the standard RDF entailment regimes. In RDF or RDFS, it is not possible to say that something is not a datatype. Applications decide what are the datatypes in their local datatype map. A datatype map cannot be specified in RDF. > So the formally correct thing to say would NOT be: > > “The value of a literal whose datatype IRI is not in the datatype map is unknown.” > > but: > > “The value of a literal whose datatype IRI does not denote a datatype in the datatype map is unknown.” Ok but "the value" seems to indicate that, although it is not know, it is a value in some kind of value space (an instance of rdfs:Literal). But it could be a resource outside the extension of rdfs:Literal. > > Oh well. > >> I would prefer to have literals of type rdf:LangString denote themselves in all interpretations rather than some unknown thing, but I don't know how best to make it happen. Clearly it can't be done through the L2V mechanism. > > That's easy – a new row in the first table in Section 1.4: > http://www.w3.org/TR/rdf-mt/#gddenot > > If E is a language-tagged string with lexical form aaa and language tag ttt in V then I(E) =<aaa,ttt> > > and appropriate exceptions have to be stated in some places that talk about datatype IRIs – “if the datatype IRI is not rdf:langString, then …” Yep, very good. > > Best, > Richard -- Antoine Zimmermann ISCOD / LSTI - Institut Henri Fayol École Nationale Supérieure des Mines de Saint-Étienne 158 cours Fauriel 42023 Saint-Étienne Cedex 2 France Tél:+33(0)4 77 42 66 03 Fax:+33(0)4 77 42 66 66 http://zimmer.aprilfoolsreview.com/
Received on Monday, 14 November 2011 15:19:11 UTC