- From: <Patrick.Stickler@nokia.com>
- Date: Thu, 27 Sep 2001 14:20:25 +0300
- To: champin@bat710.univ-lyon1.fr, www-rdf-interest@w3.org, www-rdf-logic@w3.org
> -----Original Message----- > From: ext Pierre-Antoine CHAMPIN [mailto:champin@bat710.univ-lyon1.fr] > Sent: 27 September, 2001 12:03 > To: www-rdf-interest@w3.org; www-rdf-logic@w3.org > Subject: Literals (Re: model theory for RDF/S) > > > Sorry to bring back an old debate, probably set up for everyone except > me, but their in curently another debate on rdf-logic about the model > theory, and the special case of literals make it quite complicated. > > So I ask: given the existence of a quite convinient URI > scheme 'data:', > is the Literal/Resource disctinction still necessary in RDF? > > Couldn't we consider that any literal in the syntax should be > converted > by the parser into a 'data:' URI? This does not need to alter the > syntax, and then keeps compatibility with existing RDF bits. I've been leaning towards this sort of view for awhile now. I also agree that it would make the conceptual model more consistent. > Furthermore, this would offer a straightforward solution to some > problems like expressing the xml:lang attribute in RDF. I don't think actually that it would provide a solution for that per se, as xml:lang is a property of the occurrence, not the literal. E.g. the literal byte sequence "pan" could be either English or Spanish (and possibly other languages as well) yet I would presume that <... xml:lang="en">pan</...> is a statement about the particular occurrence of the literal and not about the byte sequence "pan" in general. You wouldn't (I don't think) want to have multiple statements attributing multiple languges to a given string -- at least insofar as the intended use of xml:lang is concerned, right? I would myself love to see a data type URI approach by which otherwise "literal" values could be defined as instances of a given data type URI. E.g. dt:integer:5 dt:token:en dt:date:2001-09-27 dt:time:2000-11-01T17:32:20Z dt:float:38829.11883292 ... etc. Then, one can associate the syntax and semantics of the particular data types using RDF. Furthermore, one could say things about the data type scheme like <rdf:Description rdf:about="dt:date"> <rdfs:isDefinedBy rdf:resource="http://www.w3.org/TR/NOTE-datetime"/> <rdfs:seeAlso rdf:resource="http://www.iso.ch/iso/en/CatalogueDetailPage.CatalogueDetail?C SNUMBER=26780"/> <dt:pattern>[0-9]{4}-((0[1-9])|(1[012]))-((0[1-9])|([12](0-9))|(3[01]))</dt: pattern> <rdf:type rdf:resource="http://purl.org/dc/terms/W3CDTF"/> </rdf:Description> etc. All the info you need to constrain property ranges, perform validation of input values, and what not. (Note that the URI scheme is combined with a namespace for defining properties of namespaces (instances) of that scheme). Eh? Cheers, Patrick -- Patrick Stickler Phone: +358 3 356 0209 Senior Research Scientist Mobile: +358 50 483 9453 Nokia Research Center Fax: +358 7180 35409 Visiokatu 1, 33720 Tampere, Finland Email: patrick.stickler@nokia.com
Received on Thursday, 27 September 2001 07:20:39 UTC