RE: Literals (Re: model theory for RDF/S)

> -----Original Message-----
> From: ext Drew McDermott [mailto:drew.mcdermott@yale.edu]
> Sent: 02 October, 2001 00:26
> To: www-rdf-logic@w3.org
> Subject: Re: Literals (Re: model theory for RDF/S)
> 
> 
> 
>    [Patrick Stickler]
>    > > 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
>    > >    ...
>    > 
>    > So would I...
> 
>    Anyone else think this would be a good idea to pursue?
> 
> Yes, although it's not clear to me how we are to interpret
> dt:date:2001-09-27.  Is the idea that 'date' is a resource (namespace?
> URI?) identifying a convention for how the literal is to be parsed and
> internalized?

Basically yes. It follows a similar, though not exactly equivalent,
approach to e.g. defining how a urn:doi:10.9882 or isbn:#### URI 
would be structured and interpreted.

I'm presently working on a pair of RFCs discussing the "philosophy" behind
my idea, and detailing how I see such a scheme being defined and used in
practice, so hopefully soon I can provide more specific input to the
discussion rather than just a few comments here and there to the list.

Of course, one interesting question that arises out of such a treatment
is: Are URI scheme prefixes and URN namespace prefixes URIs? I.e.,
can one say things such as:

   <rdf:Description rdf:about="urn:doi">
      <rdfs:isDefinedBy ...>
   </rdf:Description>

or

   <rdf:Description rdf:about="isbn">
      <rdfs:isDefinedBy ...>
   </rdf:Description>

Eh?  ;-)

> Also, as written literals can't include spaces.  The literal should be
> enclosed in doublequotes, with a universal convention about how
> to put unusual characters (such as " itself) inside doublequotes.

Well, they'd be resources, encoded via URIs, not literals. So no quotes
are needed. The idea is to eliminate the need for the concept of literals
entirely from RDF, such that *everything* is a resource, period. How
any particular resource is interpreted, the semantics associated with
any class of resource, and the constraints placed on the identifier
schemes use to represent any given resource can then all be handled
in a consistent manner -- and, the serialization can be simplified since
no syntactic forms for differentiating between "literals" and resources,
nor mapping logic from those serializations (or condensed forms of
serializations) to graph representations are necessary.

More simplicity and consistency in both the semantics and syntax.

> The good thing about this proposal is that it doesn't commit anyone to
> a universal literal-syntax scheme, although all the obvious data types
> should have standard encodings.

Right. RDF remains "neutral" and the choice of any given scheme is just
like the choice of any given ontology. The more standardized the usage,
the more interchangable the knowledge and standardized solutions are
still to be promoted and pursued, but various communities can decide
themselves how they wish to realize their knowledge representations, 
by whichever vocabularies and identity schemes they feel are optimal,
yet the framework for definition of and interaction with that knowledge
remains consistent.

--

Note: I'll have to temporarily drop out of this discussion for the rest
of the week, but hope to come back to it with some substantial material
for consideration and further discussion next week (hopefully). I've
got some other stuff to do first, and I know I just can't resist the
temptation
to reply at length if I'm reading the posts ;-)

I honestly think that this issue is very, very important, and in fact I
have been chewing on this specific problem for awhile now and am certainly
looking forward to rejoining this thread shortly with some concrete 
discussion and examples.

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 Tuesday, 2 October 2001 06:09:42 UTC