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RE: Type of (the denotation of) a plain literal

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 16 Jan 2003 06:15:33 -0500
To: w3c-rdfcore-wg@w3.org
Message-id: <3E269455.8080703@research.bell-labs.com>

>
>
>> (1)  Is the following satisfiable?
>> 
>>     ex:prop rdfs:range xsd:string .
>>     ex:subj ex:prop "abc" .
>
>No. An rdfs:range assertion specifying a datatype "excludes"
>all plain literal values, because the semantics of those
>plain literals is fixed and there is no implicit datatyping
>in RDF.
>  
>
The above is satisfiable in just about any version of the RDF semantics. 
 In simple entailment and RDF entailment, rdfs:range has no built-in 
meaning.  In RDFS entailment, xsd:string is an uninterpreted class.   In 
XSD datatype entailment, the class extension of xsd:string consists of 
the data values of the XSD string datatype, which includes strings.

If you had said,  "abc"@"fr" on the other hand, it would not be 
satisfiable under XSD datatype entailment.

The rationale given is incorrect in any case.

>I would *LOVE* if the above entailed
>
>      ex:subj ex:prop "abc"^^xsd:string .
>
>but it doesn't, and can't.
>

In XSD datatype entailment it does, because the value space of  XSD 
strings is defined as finite-length sequences of characters which are 
RDF strings.  In XSD datatype entailment, both "abc" and 
"abc"^^xsd:string denote the sequence with elements 'a', 'b', and 'c'.

(Well actually the RDF MT is broken here, but the only reasonable fix 
here would make this so.)

>> (2)  Is the following satisfiable?
>> 
>>     ex:prop rdfs:range xsd:string .
>>     ex:subj ex:prop "abc"@en .
>
>No. But for the same reasons as above, in addition to
>the semantic significance of the language tag.
>

Here the *only* problem is that the value space of XSD strings does not 
include pairs of strings and language tags.

I note that the reference to RFC 3066 is not yet fixed in RDF Concepts.

Peter  F. Patel-Schneider
Bell Labs Research
Lucent Technologies
Received on Thursday, 16 January 2003 06:12:37 EST

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