Re: details of rdf:datatype?

[Patrick Stickler, Nokia/Finland, (+358 40) 801 9690, patrick.stickler@nokia.com]


----- Original Message ----- 
From: "ext Jeremy Carroll" <jjc@hplb.hpl.hp.com>
To: "Dan Connolly" <connolly@w3.org>; <w3c-rdfcore-wg@w3.org>
Sent: 14 October, 2002 15:52
Subject: RE: details of rdf:datatype?


> 
> 
> This (Dan's examples) is what I wanted, and I thought I lost a crucial
> (straw poll) vote.
> 
> http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Sep/0178.html
> item 11 -
> ACTION: 2002-09-13#8 jjc update the abstract data model in concepts doc to
> reflect the pair denoting a datatype literal
> 
> We decided that in the abstract syntax the datatyped values would be
> represented as pairs (uri and lexical value). I am not sure when the
> lexical=>value mapping takes place (it might be in Pat's court, but I got
> the impression he had lobbed it out of play).

It takes place at the application layer, which understands the
particular datatypes in question. It definitely happens outside
the scope of the RDF MT.

What the RDF MT does is set the ground rules for how such mappings
are executed and also provides an equality test for pairings having
identical datatype and lexical form. Otherwise, it's up to the
extra-RDF application operating based on the defined semantics
of the datatype (wherever/however defined) to execute the lexical
to value mappings and make any comparisons between values.

> It is clear that some aspects of the decision require systems to *know* the
> datatypes in question, and if they don't they cannot compare non-lexically
> identically values.

Correct. The RDF MT only provides a clear case of equality when
the datatype and lexical forms are the same.

> I believe we have clarified that the point at which that knowledge is needed
> is not syntactic. Whether it is in the model theory or somehow after I still
> don't know.

I agree it is definitely not syntactic. I consider it semantic, and
outside/above the scope of the RDF MT, but constrained in critical
ways by the RDF MT.

And because it is outside/above the scope of the RDF MT, all the
abstract syntax should reflect are the pairings, not the values
or anything else relating to the lexical to value mapping.

Patrick


> Jeremy
> 
> 
> (I will do the abstract syntax update today or tomorrow - Graham can I have
> a lock on the file?)
> 
> > -----Original Message-----
> > From: w3c-rdfcore-wg-request@w3.org
> > [mailto:w3c-rdfcore-wg-request@w3.org]On Behalf Of Dan Connolly
> > Sent: 14 October 2002 14:40
> > To: w3c-rdfcore-wg@w3.org
> > Subject: details of rdf:datatype?
> >
> >
> >
> > I'm puzzling thru the details of the [6Sep] decision.
> >
> > It seems to specify that this holds:
> >
> > :jenny :age <...#integer>"10".
> > =>
> > :jenny :age <...#decimal>"10".
> >
> >
> > since those two literals denote the same value.
> >
> > and this one holds:
> >
> > :jenny :age <...#decimal>"010".
> > =>
> > :jenny :age <...#decimal>"10".
> >
> > If somebody would please confirm, I'd appreciate it.
> >
> > But I don't see how this works for an open-ended set
> > of datatypes. Does this hold?
> >
> > :jenny :age <http://example/vocab#type1>"hello".
> > =>
> > :jenny :age <http://example/vocab#type2>"hello".
> >
> > If type1 and type2 map hello to the same value, it does hold.
> >
> > Likewise, if type1 maps hello1 and hello2 to the
> > same value, then the following holds:
> >
> > :jenny :age <http://example/vocab#type1>"hello1".
> > =>
> > :jenny :age <http://example/vocab#type1>"hello2".
> >
> > It seems to me that a parser should raise an exception
> > if it sees rdf:datatype used with a value it doesn't
> > recognize. Recognizing datatypes is a parse-time thing;
> > you can't do lazy-evaluation of the type-uri/string-val
> > pair.
> >
> > Is that the design folks have in mind?
> >
> >
> > [6Sep] Draft minutes: telecon 2002-09-06 Jan Grant (Fri, Sep 06 2002)
> > http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Sep/0081.html
> >
> > =>
> > http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Aug/0257.html
> >
> > =>
> > http://www-nrc.nokia.com/sw/rdf-datatyping.html
> > http://lists.w3.org/Archives/Public/www-archive/2002Aug/0111.html
> >
> >
> > --
> > Dan Connolly, W3C http://www.w3.org/People/Connolly/
> >
> >
> >
>

Received on Monday, 14 October 2002 09:40:51 UTC