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Re: plain literals without language tag compare xsd:string in RDF

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Sat, 8 Mar 2008 10:16:01 -0500
Message-Id: <1E79584C-176B-478B-9ACC-1E469728032C@gmail.com>
Cc: Pat Hayes <phayes@ihmc.us>, public-awwsw@w3.org, "Carroll, Jeremy John" <jeremy.carroll@hp.com>, Sandro Hawke <sandro@w3.org>
To: "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>

All right, I see (RDF-MT) :
> These rules may not provide a complete set of inference principles  
> for D-entailment, since there may be valid D-entailments for  
> particular datatypes which depend on idiosyncratic properties of  
> the particular datatypes, such as the size of the value space (e.g.  
> xsd:boolean has only two elements, so anything established for  
> those two values must be true for all literals with this datatype.)  
> In particular, the value space and lexical-to-value mapping of the  
> XSD datatype xsd:string sanctions the identification of typed  
> literals with plain literals without language tags for all  
> character strings which are in the lexical space of the datatype,  
> since both of them denote the Unicode character string which is  
> displayed in the literal; so the following inference rule is valid  
> in all XSD-interpretations. Here, 'sss' indicates any RDF string in  
> the lexical space of xsd:string.
>
> xsd 1a:  uuu aaa "sss" => uuu aaa "sss"^^xsd:string .
> xsd 1b:  uuu aaa "sss"^^xsd:string => uuu aaa "sss".
> Again, as with the rules rdfD2 and rdfD3, applications may use a  
> systematic replacement of one of these equivalent forms for the  
> other rather than apply these rules directly.
>
>

Regrettably, SPARQL uses the RDFS syntactic equality in its  
definition of equality for literals :(

I wonder what RIF is planning to do

-Alan




On Mar 7, 2008, at 10:31 AM, Williams, Stuart (HP Labs, Bristol) wrote:

> Alan,
>
> I raised you question with my colleague, Jeremy Carrol (Cc'd) who  
> responded as follows:
>
> <quote>
> They are identical
>
> "foo" owl:sameAs "foo"^^xsd:string .
>
> is necessarily true.
>
> http://www.w3.org/2000/10/rdf-tests/rdfcore/datatypes/test011a.nt
> entails
> http://www.w3.org/2000/10/rdf-tests/rdfcore/datatypes/test011b.nt
> as recorded in the RDF Test Cases doc
>
> Jeremy
> </quote>
>
> In a further exchange he also confirmed/clarified that it is  
> neccessarily the case that:
>
>         "1234" owl:sameAs "1234"^^xsd:string .
>
> ie. (I think) that means that:
>
>         "1234" owl:sameAs "1234"^^xsd:integer .  ## or some other  
> numeric datatype.
>
> is necessarily false (which is what I would expect).
>
> Cheers,
>
> Stuart
> --
> Hewlett-Packard Limited registered Office: Cain Road, Bracknell,  
> Berks RG12 1HN
> Registered No: 690597 England
>
>
>> -----Original Message-----
>> From: public-awwsw-request@w3.org
>> [mailto:public-awwsw-request@w3.org] On Behalf Of Alan Ruttenberg
>> Sent: 04 March 2008 15:29
>> To: Pat Hayes
>> Cc: public-awwsw@w3.org
>> Subject: plain literals without language tag compare xsd:string in  
>> RDF
>>
>>
>> Is there any utility to having these being disjoint classes?
>> It would seem to me that it would be more sensible to say
>> that any string that doesn't have a  language type or a
>> datatype is inferred to be of type xsd:string.
>>
>> Did this situation come about because it was easier to make
>> the RDF semantics look cleaner, or was there some principled
>> reason for making the distinction?
>>
>> -Alan
>>
>>
>>
Received on Saturday, 8 March 2008 15:16:17 GMT

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