W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > March 2003

Aggenda item: RE: pfps-08 last call comment on typed literals

From: <Patrick.Stickler@nokia.com>
Date: Fri, 21 Mar 2003 10:15:23 +0200
Message-ID: <A03E60B17132A84F9B4BB5EEDE57957B01B90C1C@trebe006.europe.nokia.com>
To: <w3c-rdfcore-wg@w3.org>
Cc: <pfps@research.bell-labs.com>


I have to agree with Peter on the point made below, and propose that
the WG do one of two things to correct it:

1. Define XMLLiteral as an rdfs:Datatype with no exceptional
   interpretation (i.e. lang tags are not relevant to the L2V
   mapping).

2. Define XMLLiteral not as an rdfs:Datatype, but as a special
   literal node type similar to plain literal nodes, whereby
   D-interpretations do not apply.

My own preference would be #1, but as it seems a good number of
folks still think xml:lang should infect XML literals, I think
that #2 would be the most widely acceptable solution.

#2 essentially means that both plain and XML literals remain
exactly as defined by M&S, and typed literals are something
completely new, and not affecting any existing literals defined
in terms of M&S.

Brian, could this issue be added to today's aggenda?

Cheers,

Patrick


> I also do not view this response as acceptable for technical reasons:
> 
> 1/
> 
>  From http://www.w3.org/TR/2003/WD-rdf-mt-20030123/
> 
> In an RDFS interpretation I (see section 3.3)
>          I(rdf:XMLLiteral) in ICEXT(I(rdfs:Datatype))
> In a D-interpretation, for any D (see Section 3.4)
>          ICEXT(I(rdfs:Datatype)) = D
> 
> Therefore, in any D-interpretation, for any D, there must be 
> a member of D
> that is a standard datatype corresponding to rdf:XMLLiteral.
> 
> This means that any set of datatypes includes a datatype for
> rdf:XMLLiteral, and this datatype has a L2V mapping that takes lexical
> forms (in the form of strings *without* language tags) to resources.
> Any specification of D-interpretations must include this mapping.
> 
> This superfluous mapping cannot be accessed from RDF, but can 
> in OWL, for
> example by
> 
>          rdf:XMLLiteral owl:sameIndividualAs ex:foo .
>          ex:bar ex:baz "55"^^ex:foo .
> 
> I do not view this as an acceptable situation, if only for semantic
> cleanliness reasons.
> 
> This situation is not improved in the current editor's draft.
> 
> 2/
> 
> Even if this issue were to be solved, I believe that OWL 
> should have the
> following sort of entailment hold:
> 
>          rdf:XMLLiteral owl:sameIndividualAs ex:foo .
>          _:x owl:sameIndividualAs "..."@en^^rdf:XMLLiteral .
>          _:y owl:sameIndividualAs "..."@en^^ex:foo .
> 
> entails
> 
>          _:x owl:sameIndividualAs _:y .
> 
> (This entailment holds for every URI reference except rdf:XMLLiteral.)
> 
> However, there is no way for OWL to do this, because typed 
> literals that
> include ex:foo are interpreted by the rules for non-built-in 
> datatypes and
> there is no way to specify a non-built-in datatype that works 
> the same way
> as rdf:XMLLiteral.
> 
> I do not view this as an acceptable situation.
> 
> 
> Peter F. Patel-Schneider
> Bell Labs Research
> Lucent Technologies
> 
> 
> 
Received on Friday, 21 March 2003 03:15:26 EST

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:56:14 EDT