W3C home > Mailing lists > Public > www-rdf-logic@w3.org > July 2002

Re: Input sought on datatyping tradeoff

From: Graham Klyne <GK@ninebynine.org>
Date: Sat, 13 Jul 2002 06:48:33 +0100
Message-Id: <5.1.0.14.2.20020713064418.03867770@joy.songbird.com>
To: "Thomas B. Passin" <tpassin@comcast.net>
Cc: www-rdf-logic@w3.org

At 07:03 PM 7/11/02 -0400, Thomas B. Passin wrote:
> >    <Jenny> <ageInYears> "10" .
> >    <Jenny> <testScore>  "10" .
> >
> > Should an RDF processor conclude that the value of Jenny's ageInYears
> > property is the same as the value of Jenny's testScore property?
>
>I do not think this question is well posed.  On what basis will an RDF
>processor use these literal values for anything?  They cannot be used as the
>subjects of statements as things stand now.  RDF as a language does not
>really provide the ability to do anything except provide a graph or data
>store of triples.  To answer the question as posed, we must imagine some
>logic processor or query engine, or RDF processor with extensions.  Are we
>then trying to imagine what would support some "reasonable" set of
>processors? Or are we really talking only about "RDFS-aware" processors?

But RDF _is_ (a very little) more than a store of triples.  It has some 
simple notions of entailment.  That's what the formal semantics 
provide.  So Brian's question does presume a processor that understands 
logic to the extent of entailments that are sanctioned by the RDF(S) formal 
semantics.

The above question (Brian's question a) does not presume entailments 
sanctioned by any semantics other than basic RDF.  It is simply:  does a 
given literal always denote the same thing?  If so, then a "yes" answer 
follows from the instance lemma (http://www.w3.org/TR/rdf-mt/).  (i.e. if 
the strings always denote the same thing, then they can all be replaced by 
a bnode denoting the same thing, and the result follows.)

The other question (Brian's question d) presumes entailments sanctioned by 
RDF + RDF schema + RDF datatyping semantics.

(BTW, because queries bring their own set of potential unknowns, I prefer 
to think of this question simply in terms of entailments.)

#g


-------------------
Graham Klyne
<GK@NineByNine.org>
Received on Saturday, 13 July 2002 02:47:45 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Monday, 7 December 2009 10:52:42 GMT