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Re: RDF 1.1 Semantics: completeness for lang-tag variants

From: Peter F. Patel-Schneider <Peter.Patel-Schneider@nuance.com>
Date: Thu, 25 Sep 2014 15:57:13 -0700
Message-ID: <54249DC9.3030804@nuance.com>
To: Aidan Hogan <aidhog@gmail.com>, "<public-rdf-comments@w3.org>" <public-rdf-comments@w3.org>
This is an unofficial reply.

In the RDF 1.1 semantics, language tags are always in lower case.  This can be 
seen in Section 3.3 of RDF 1.1 Concepts,
   The value space of language tags is always in lower case.
Admittedly, this could have been stated better.

peter


On 09/25/2014 03:30 PM, Aidan Hogan wrote:
> Hi,
>
> In the RDF 1.1 Semantics document, in "A. Entailment Rules", the following
> completeness result is given:
>
> «
> If S is RDF (RDFS) consistent, then S RDF entails (RDFS entails) E just when
> the generalized RDF (RDFS) closure of S towards E simply entails E.
> »
>
> But I'm not sure what part of the entailment procedure deals with the case
> insensitivity of language tags or optionality of xsd:string.
>
> For example, let S be:
>
>      ex:a ex:b "c"@en-US .
>
> and let E be:
>
>      _:a ex:b "c"@en-us .
>
> If I'm correct, S RDF(S) entails E. But I cannot see how either the
> generalized RDF(S) closure or simple entailment cover this.

The value corresponding to the literal "c"@en-US is the same as the value 
corresponding to the literal "c"en-us.

>
> Likewise what happens if S is:
>
>      ex:a ex:b "c"^^xsd:string .
>
> and E is something like:
>
>      _:a ex:b "c" .

Again, the values are the same.  See Section 3.3 of RDF 1.1 Concepts.
>
> I likewise cannot see how this case is covered?
>
>
> Is a canonicalisation step not needed somewhere to lower-case all language
> tags and add xsd:string to all "plain literals" in S and E?

Well, not really.  The values are already in a form that does not require 
further canonicalization.

>
>
> Best,
> Aidan
>
Received on Thursday, 25 September 2014 22:57:45 UTC

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