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Re: Proposal for ISSUE-12, string literals

From: Ivan Herman <ivan@w3.org>
Date: Wed, 18 May 2011 12:56:19 +0200
Cc: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <DFE7AFBC-19A8-4928-B392-102C6B3068D2@w3.org>
To: Steve Harris <steve.harris@garlik.com>

On May 18, 2011, at 11:12 , Steve Harris wrote:
[snip]

> 
> I don't know what "match" means in a model theoretic sense, only in a RFC 4647 sense.
> 
>> :a :b "chat"@en-GB .
>> 
>> entail
>> 
>> :a :b "chat"@en .
>> 
>> in any entailment regime defined by the RDF semantics ??
> 
> No idea.
> 

AFAIK, the answer is no, because the semantics does not say anything about language tags (apart from the fact that it exists). But in case we introduce these as datatypes, we should at least make it clear that the value space of one is a subspace of another one. AFAIK, the RDFS semantics does not require to define the corresponding datatypes as being subclasses of the other, but implementation may then do that.

Ivan



>> I don't think so, which does not mean that it is not an interesting
>> thing to consider —although it looks like a tricky can of worms...
>> 
>> In any case, I don't think that this entailment would mean that
>> rdflang:en would be a supertype of rdflang:en-GB, as their value space
>> would still be disjoint, in my view.
> 
> OK, seems reasonable.
> 
> - Steve
> 
>>>>>> A few practical considerations:
>>>>>> 
>>>>>> 1) ISO language codes are not case sensitive, IRIs are. "foo"@fr =
>>>>>> "foo"@FR, "foo"^^rdflang:fr != "foo"^^rdflang:FR. We'd need to define a
>>>>>> canonical case for the datatype form.
>>>>> 
>>>>> I hadn't thought of that either, but yes, canonical case sounds like the
>>>>> right thing to do.
>>>> 
>>>> and according to [1] again, the language tag is normalized to lowercase
>>>> in the abstract syntax.
>>> 
>>> OK, that's easy.
>>> 
>>>> <snip />
>>>>>> 4) Is the value space all UTF-8 strings? If not, is it a type error
>>>>>> to write "מחשב"^^rdflang:en?
>>>>> 
>>>>> well, currently I guess any UTF-8 string is valid. So yes, the value
>>>>> space would of all those datatypes would be all UTF-8 strings, if only
>>>>> for the sake of BC (and because I sure don't want to walk down that path...)
>>>> 
>>>> sorry, I was reading "lexical space".
>>>> 
>>>> The value space would be isomorphic to the set of UTF-8 strings, but
>>>> different for each "language datatype". Defining it as the set of pair
>>>> <text, language-tag> as in RDF Semantics seems like a good option.
>>> 
>>> Sounds reasonable.
>>> 
>>> - Steve
>>> 
>> 
> 
> -- 
> Steve Harris, CTO, Garlik Limited
> 1-3 Halford Road, Richmond, TW10 6AW, UK
> +44 20 8439 8203  http://www.garlik.com/
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> 
> 


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Received on Wednesday, 18 May 2011 10:54:31 GMT

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