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Re: functions detail: lang/langmatches

From: Steve Harris <steve.harris@garlik.com>
Date: Wed, 3 Nov 2010 15:45:04 +0000
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <310C1B58-F585-46A1-B9A2-7A8254D20C7A@garlik.com>
To: Axel Polleres <axel.polleres@deri.org>
On 2010-11-03, at 13:19, Axel Polleres wrote:

> Hi all,
> 
> A user just made me aware of a small editorial detail we could improve in the query spec to explain lang/langmatches better:
> We have the following example for lang in the spec: http://www.w3.org/TR/rdf-sparql-query/#func-lang
> 
> Data:
> 
> @prefix foaf:       <http://xmlns.com/foaf/0.1/> .
> 
> _:a  foaf:name       "Robert"@EN.
> _:a  foaf:name       "Roberto"@ES.
> _:a  foaf:mbox       <mailto:bob@work.example> .
> 
> This query finds the Spanish foaf:name and foaf:mbox:
> 
> PREFIX foaf: <http://xmlns.com/foaf/0.1/>
> SELECT ?name ?mbox
> WHERE { ?x foaf:name  ?name ;
>            foaf:mbox  ?mbox .
>         FILTER ( lang(?name) = "ES" ) }
> 
> 
> Since the example comes before langMatches http://www.w3.org/TR/rdf-sparql-query/#func-langMatches
> users may be inclined to read that this is the way to match language tags.
> 
> The suggestion to improve this is as follows:
> 
> 1)Add a triple to the graph of the example of lang, i.e.
> 
> Data:
> 
> @prefix foaf:       <http://xmlns.com/foaf/0.1/> .
> 
> _:a  foaf:name       "Robert"@EN.
> _:a  foaf:name       "Roberto"@ES.
> _:a  foaf:name       "roberto"@es.
> _:a  foaf:mbox       <mailto:bob@work.example> .
> 
> 2) and after the result add a note with a forward-reference to langMatches, e.g.:
> "
> Note that "roberto"@es is not returned here returned since "=" used in this FILTER checks for string equality in a case-sensitive manner.
> For more general matching of lang-tags, please refer to the function <a href="#func-langMatches>langMatches</a> explained below.
> " 
> 
> Opinions on this suggestion? I am neutral on it, but think it wouldn't do harm.

There might be issues around legal entailments too, I seem to remember that 4store normalises ISO language identifiers, and that this is legal by whatever RFC defines them.

- Steve 

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Received on Wednesday, 3 November 2010 16:07:38 GMT

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