Re: Rethinking ISSUE-12 with lang datatypes

On May 27, 2011, at 11:23 , Andy Seaborne wrote:

> On 25/05/11 17:50, Antoine Zimmermann wrote:
>> All,
>> [disclaimer: I am not vehemently in favour of that proposal, just expressing my thoughts aloud.]
> In the same spirit: just thinking aloud.


> One of the limitations of datatypes is that lexical space is a 1D, the set of sequences of characters.  If we generalise datatypes for RDF to a "representation space" which can be multi-dimensional, we can formulate and relate language tagged datatypes quite simply.
> Restricting the representation space to 1D space of strings, we get back to lexical space and compatibility with XSD etc.
> rdf:String is a datatype where the rep space is
>    (unicode strings) union (unicode strings, validLangTags)
> The value space is <string> union <string,validLangTags>
> rdf:LangTaggedString is a derived datatype of rdf:String, restricting the  represenation space to (unicode strings, validLangTags).
> rdf:lang{langTag} is a derived datatype of rdf:LangTaggedString, restricting the representation space to (unicode strings, {langTag})

But, I believe, the alternative idea was slightly different. If we remove rdf:LangTaggedString from the equation altogether, and we keep only the rdf:lang-{langtag} as a series of datatypes, then the representation space is simply unicode strings plus a specific datatype. Ie, just like we have


that are (afaik) disjoint as different, we would have



"a" is a shortcut for "a"^^xsd:string
"a"@en is a shortcut for "a"^^rdf:lang-en

there is a question whether we would define rdf:lang-en as a subtype (subclass) of xsd:string; and it seems to be safer not to do that. 

SPARQL str() 

returns the unicode string and drops the datatype for all combination.


> "foo"@en is special syntax ("foo", "en").
> (c.f. 123 for "123"^^xsd:string)
> SPARQL str() is defined to return the first element of a tuple.
> Then rdf:PlainLiteral is datatype with a 1D lexical space, encoding using "@" as a separator.
> (Does it say anywhere in RDF that derived datatypes must be subclasses?)
> 	Andy

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Friday, 27 May 2011 09:47:15 UTC