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Re: getting language tags out of the fundamental model (ISSUE-12)

From: Ivan Herman <ivan@w3.org>
Date: Wed, 1 Jun 2011 08:43:40 +0200
Cc: public-rdf-wg@w3.org
Message-Id: <A9460E0C-6B42-4585-98F6-20268AAB44F1@w3.org>
To: Andy Seaborne <andy.seaborne@epimorphics.com>
Andy,

On May 31, 2011, at 19:28 , Andy Seaborne wrote:

> 
>>>> Modelling everything at a very fine grained level moves the burden on
>>>> to the application.
>>>> 
>>>> c.f. RDF containers and collections.
>>> 
>>> 
>>> Conditionally, yes. It would only arise when language tags are used.
>>> Most strings do not use language tags.
> 
> 1/ We find that there can be very lang-tag intensive datasets.  For example, data from Wales.
> 
> 2/ Don't we have a new variability to deal with:
> 
> <s> skos:altLabel
>   [ a rdf:LinguisticExpression;
>       rdf:language "bar";
>       rdf:value "foo"] .
> 
> <s> skos:altLabel "foo" .
> 
> 
> And
> 
> { <s> skos:altLabel ?altLabel }
> 
> get us back to same problems of RDF collections and a round trip to get the next step in the information (assuming skolemization).
> 
>>> The question is, IMO, whether the benefit of fixing the equivalences
>>> between RDF strings is worth the pain to be experienced by users of
>>> language tags in this context. *Personally* I would rather query the
>>> above pattern than need to guess whether a string is a plain literal
>>> or a language tagged string or an xsd:string.
> 
> Not sure it's a guess unless we do nothing.  At least they are all a single RDF term that can be queries then inspected.
> 
> People here seem to want a datatype for all literals.
> 
> If every plain literal now has a datatype, xsd:string or rdf:LangString (or other name), and use LANG knowing that rdf:LangString  means use LANG to ask further i.e. Value space of ("foo", "en").
> 
> rdf:lang-{langTag} requires dereferencing to get the language (or IRI mangling but maybe some invented a different IRI - no unique names here!)

Just to check my understanding; what you are saying is:

- if one goes along the lines originally proposed by Richard, ie, using rdf:LangString (or some similar name) then any SPARQL query involving a language becomes a bit cleaner because one can use lang(?v) in a FILTER or (in SPARQL 1.1) in an AS; whereas
- if one defines a series of rdf:Lang-{langname} then queries (or applications) will have to fiddle around interpreting the URI-s.

And that is quite a compelling argument against rdf:Lang-{langname} to me, I must admit

Ivan


> 
> 	Andy
> 
> 
>>> 
>>> Regards,
>>> Dave
>>> 
>>> 
>>> 
>>>> 
>>>> Andy
>>>> 
>>> 
>> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
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Received on Wednesday, 1 June 2011 06:41:21 GMT

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