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Re: URI aliases for RDF terms?

From: Eric Prud'hommeaux <eric@w3.org>
Date: Sat, 12 Nov 2011 18:06:02 -0500
To: Richard Cyganiak <richard@cyganiak.de>
Cc: Ivan Herman <ivan@w3.org>, Steve Harris <steve.harris@garlik.com>, Ian Davis <ian.davis@talis.com>, W3C RDF WG <public-rdf-wg@w3.org>
Message-ID: <20111112230602.GM21969@w3.org>
* Richard Cyganiak <richard@cyganiak.de> [2011-11-09 21:23+0000]
> On 9 Nov 2011, at 20:26, Eric Prud'hommeaux wrote:
> >> IMO W3C should:
> >> 
> >> 1. Assign short URIs in a *single* namespace for all RDF and RDFS (and possibly OWL and XSD) concepts *now*
> >> 2. Leave it up to individual WGs to adopt those short URIs at their own leisure
> >> 3. Leave it up to implementers to add support for them already
> >> 4. The RDF WG should *not* do anything about them in RDF 1.1, but perhaps in RDF 2.0
> > 
> > Every evolution path I see from this leads to either fragmentation or unrealistic implementation demands. The options I see are:
> >  a. do nothing.
> >  b. gradual introduction of redundant short terms, followed by gradual redaction of longer names. -- good bye cardinality
> >  c. international change-over day. -- all the air traffic control and clinical support systems relying on RDF will crash that day.
> >  d. stake out short syntactic forms for use in turtle in SPARQL but leave the denotations the same.
> 
> Consider the evolution path for unifying "foo" and "foo"^^xsd:string: Both exist side by side in the wild and query authors have to deal with that. Increasingly, we will have systems that know that both are equivalent, e.g., those with D-entailment support and those with RDF 1.1 support. Both forms will continue to be deployed in the wild forever but which one to use will be merely a matter of taste.
> 
> It would be the same with <http://n.w3.org/rdf/type> and <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>. Just replace “D-entailment” with “owl:equivalentProperty entailment” and “RDF 1.1” with “RDF 2.0”.

It was my impression that we decided that, for RDF 2012, "foo" is a shorthand for "foo"^^xsd:string. That is
Data:
  <x> <p> "foo", "foo"^^xsd:string .
Query:
  SELECT ?s { ?s <p> ?o }
Results (RDF 2004):
  ?s
  <x>
  <x>
Results (RDF 2012):
  ?s
  <x>
and that we justified this by saying that no one really ever wanted them to be different in the first place. 

Following this scenario, we could say that <http://n.w3.org/rdf/type> and <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> are the same node but then what is STR(<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>)?
(I reallize that I betray my bias by casting everything in terms of query, but I think that SPARQL is the most used and useful tool in the SemWeb toolbox.)

If I misunderstand, we have instead decided that D-entailment gives us two nodes,
Data:
  <x> <p> "foo" .
Query:
  SELECT ?s { ?s <p> ?o }
Results (RDF + D-entailment 2012):
  ?s
  <x>
  <x>
then I'm skeptical that we've simplified anything. (But I'll go along with it if SELECT (SUM(?salary) AS ?checkAmount) { ?who foaf:given_name "eric" ; mit:salary ?salary } doubles my salary.)


> Best,
> Richard

-- 
-ericP
Received on Saturday, 12 November 2011 23:06:33 GMT

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