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Re: Proposal for ISSUE-12 language-tagged literals

From: Antoine Zimmermann <antoine.zimmermann@insa-lyon.fr>
Date: Thu, 14 Jul 2011 09:36:42 +0200
Message-ID: <4E1E9C8A.7010806@insa-lyon.fr>
To: public-rdf-wg@w3.org
In your proposal, rdf:Text is equivalent to rdf:PlainLiteral so it seems 
redundent.
Moreover, rdf:PlainLiteral was originally called rdf:text (see 
http://www.w3.org/TR/2009/WD-rdf-text-20090421/ for instance) but this 
name was rejected because the concept of "text" includes many other 
features like directionality, font, structure, etc.
I suggest some changes below:

Le 13/07/2011 16:51, Richard Cyganiak a écrit :
> We have addressed one half of ISSUE-12, the half about string literals *without* language tags.
>
> Here's a proposal for the other half, string literals *with* language tags and rdf:PlainLiteral. This is a very minimalist proposal.
>
> Summary:
> - add classes rdf:LangString and rdf:Text so we can better specify string literals as rdfs:range of properties

don't add rdf:Text.

> - add the technical term “language-tagged string” as an alternative to the current “plain literal with language tag”
> - ask OWL and RIF WGs to update rdf:PlainLiteral document to reflect the RDF WG decisions
>
> (This completes my ACTION-62.)
>
> Best,
> Richard
>
>
> [[
>
> A literal is either a typed literal or a language-tagged string.
>
> A language-tagged string is an<Unicode string, language tag>  pair.
>
> "Plain literal with language tag" (from RDF 2004) is an alternative term for "language-tagged string". They are the same thing.
>
> rdf:LangString is the class of all language-tagged strings. It can be used in rdfs:range statements.
>
> rdf:Text is the class of all language-tagged strings and all Unicode strings. It can be used in rdfs:range statements.

remove this line.

> The RDF Concepts document is updated with the definitions above. No other changes to RDF Concepts.
>
> The RDF Semantics document is updated to make rdf:LangString and rdf:Text work. No other changes to RDF Semantics.

remove "and rdf:Text"

> The RDF Schema document is updated to add rdf:LangString and rdf:Text. No other changes to RDF Schema.

remove "and rdf:Text"

> The SPARQL WG is asked to *consider* whether DATATYPE("foo"@en) should return rdf:LangString instead of error.

if rdf:LangString is not a datatype, then I think SPARQL should'nt 
return it. Does SPARQL return rdfs:Literal?

> The OWL and RIF WGs are asked to make changes to the rdf:PlainLiteral specification:
>
> - Clarify that the purpose of the document is *solely* to provide
>    compatibility between RDF and specifications whose literal
>    design does not support language tags.

It is not the only purpose of rdf:PlainLiteral. The essential purpose, 
AFAIK, is to allow systems to type all literals. It also makes possible 
the definition of complex datatypes (for instance, it is possible to 
define a datatype equivalent to your rdf:LangString, or to the 
English-tagged strings, etc). Without a proper datatype for that, such 
definitions are not possible.

> - The spec should be changed to *only* cover strings *with* language
>    tags, because strings without language tags now always have a
>    datatype (xsd:string) and therefore don't need to be covered in this
>    spec.
>
> - Instead of defining its complete own datatype rdf:PlainLiteral,
>    the spec should only extend the rdf:LangString class so that
>    it can serve as a datatype.
>
> ]]


-- 
Antoine Zimmermann
Researcher at:
Laboratoire d'InfoRmatique en Image et Systèmes d'information
Database Group
7 Avenue Jean Capelle
69621 Villeurbanne Cedex
France
Tel: +33(0)4 72 43 61 74 - Fax: +33(0)4 72 43 87 13
Lecturer at:
Institut National des Sciences Appliquées de Lyon
20 Avenue Albert Einstein
69621 Villeurbanne Cedex
France
antoine.zimmermann@insa-lyon.fr
http://zimmer.aprilfoolsreview.com/
Received on Thursday, 14 July 2011 07:37:14 GMT

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