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Re: So now we have tidy literals...

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Tue, 15 Oct 2002 10:00:49 +0300
Message-ID: <002501c27418$982824c0$544516ac@NOE.Nokia.com>
To: "ext Dan Connolly" <connolly@w3.org>, "Graham Klyne" <Graham.Klyne@MIMEsweeper.com>
Cc: "Brian McBride" <bwm@hplb.hpl.hp.com>, "RDF core WG" <w3c-rdfcore-wg@w3.org>



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


----- Original Message ----- 
From: "ext Dan Connolly" <connolly@w3.org>
To: "Graham Klyne" <Graham.Klyne@MIMEsweeper.com>
Cc: "Brian McBride" <bwm@hplb.hpl.hp.com>; "RDF core WG" <w3c-rdfcore-wg@w3.org>
Sent: 14 October, 2002 17:34
Subject: Re: So now we have tidy literals...


> 
> On Mon, 2002-10-14 at 07:42, Graham Klyne wrote:
> > 
> > At 08:30 AM 10/14/02 +0100, Brian McBride wrote:
> > 
> > >At 16:49 11/10/2002 +0100, Graham Klyne wrote:
> > >
> > >>Now that we have tidy literals, do we actually agree what (tidy) kind of 
> > >>thing they actually denote, so we can say something sensible in the 
> > >>concepts document?
> > >>
> > >>I.e., in:
> > >>
> > >>   Jenny age "10" .
> > >>
> > >>is there anything to say about what the "10" actually denotes?
> 
> Well, it's identical to what "10" denotes anywhere else in
> n-triples, and it's distinct from what "010" denotes,
> and from what "abc" denotes, and so on.
> 
> > >> From past discussion, I'm expecting that the answer will be that a 
> > >> literal denotes a composite value consisting of a Uniocode string, a 
> > >> language code and an XML flag, or something of that kind.  That would 
> > >> tally with the current abstract syntax description [1].
> > >
> > >Right, though DanC has been suggesting we consider that we two types of 
> > >literals, each a pair of the literal and the string, one is a bare literal 
> > >and the other is an xml literal.
> > 
> > Yes... I think I came closer to that in the tentative text, which you did 
> > not quote.  But mainly, I wanted to make sure we're all facing the same 
> > direction now ;-)
> 
> I'm confused by the above.
> 
> It seems to me that the class of Literals is a sort of union:
> 
> 1.a strings, resulting from
> <title>abc</title>
> where no xml:lang dominates the <title> propElt
> 
> 1.b lang-strings, resulting from
> <title xml:lang="en">abc</title>
> 
> 2.a XML infoset thingies, resulting from
> <title rdf:parseType="Literal">some <em>very</em> good
> stuff</title>
> [some text earlier in a thread said that this was a
> unicode string; I wouldn't say that; it can be serialized as
> a unicode string, as we do in n-triples. But that doesn't
> make it a string]
> 
> 2.b XML infoset thingies, with lang, resulting from
> <title xml:lang="en"
> rdf:parseType="Literal">some <em>very</em> good
> stuff</title>
> 
> 3.a datatype values, resulting from
> <date rdf:datatype="&xsd;date">2000-10-12</date>
> These consist of an absolute URI reference
> and a unicode string.
> 
> I dunno if we have 3.b lang-datatype-values. I hope not.

I think not.

> Nor do I know if datatype values of type &xsd;string are
> identical to normal 1.a strings. It seems best, for users,
> if they are, but it's sort of an ugly special case.

This isnt' possible to test at the RDF layer, because
xsd:string is not understood by RDF. It's no more understood
than foo:blargh. 

Yes, intuitively, we can say that the entailment below should
hold at an application layer which groks xsd:string, but
that's not an RDF-entailment.

Patrick


> Test case:
> 
> <rdf:Description rdf:about="#something">
>   <p1>abc</p1>
>   <p2 rdf:datatype="&xsd;string">abc</p2>
> </rdf:Description>
> 
> entails?
> 
> <rdf:Description rdf:about="#something">
>   <p1 rdf:nodeID="X" />
>   <p2 rdf:nodeID="X" />
> </rdf:Description>
> 
> (please add that to the test collection, Jeremy/Jan/et. al.)
> 
> -- 
> Dan Connolly, W3C http://www.w3.org/People/Connolly/
> 
> 
Received on Tuesday, 15 October 2002 03:02:48 EDT

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