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Re: reopen ISSUE-97 and reclose next week - should interpretations be relative to a vocabulary

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Thu, 07 Mar 2013 15:58:58 +0100
Message-ID: <5138AB32.6060009@emse.fr>
To: public-rdf-wg@w3.org

Le 06/03/2013 19:30, Peter Patel-Schneider a écrit :
> I propose that we reopen ISSUE-97 and resolve it differently at the
> teleconference next week.
> ISSUE-97 concerns whether
> ex:john ex:age "22"^^xsd:integer
> {xsd:integer}-entails
> ex:john ex:age "+22"^^xsd:integer

This has been decided to be solved independently of ISSUE-97.
Thinking about it, the idea to make the mapping IL partial is good if 
interpretations do not depend on a vocabulary, since it does not force 
all literals to denote.

> or the empty graph RDFS-entails
> ex:john rdf:type rdfs:Resource
> In the 2004 version of RDF these entailments do *not* hold, the first
> because there are {xsd:integer}-interpretations where "22"^^xsd:integer is
> in the vocabulary but "+22"^^xsd:integer is not.   I believe that all RDF
> implementations do *not* work this way.  Instead they take the very
> reasonable idea that all interpretations involved in the reasoning must
> interpret all the vocabulary in both the LHS and the RHS.

I don't believe that all implementations make "ex:john rdf:type 
rdfs:Resource" true in all cases.

Consider the following. According to SPARQL 1.1 with RDFS entailment regime:

ASK WHERE { <myURI>  a  rdfs:Resource }

must return false if <myURI> is not a term in the dataset.
The easiest way to implement that is to use a reasoner that implements 
RDF 2004 Semantics. If one uses a reasoner that implements RDF 1.1 
Semantics (as currently written), one has to be careful with such cases.

> The semantics should be modified to make it clear that entailment should
> work the way that everyone thinks it does.  The current editor's draft of
> the semantics changed interpretations so that they are no longer relative
> to a vocabulary, but instead interpret all IRIs and all well-typed literals
> (and no ill-typed literals).  I believe that no changes are needed in any
> other WG document, and that the change conforms to the universal
> implementation of RDF.   This change has the desired effect and should be
> adopted by the working group.

Fair enough, we can agree on this with a resolution next week, if 
everyone approves.


> Peter F. Patel-Schneider
> Nuance Communications

Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
Tél:+33(0)4 77 42 66 03
Fax:+33(0)4 77 42 66 66
Received on Thursday, 7 March 2013 14:59:29 UTC

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