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

From: Jos De_Roo <jos.deroo@agfa.com>
Date: Thu, 16 Jan 2003 17:43:55 +0100
To: pfps@research.bell-labs.com
Cc: w3c-rdfcore-wg@w3.org, w3c-rdfcore-wg-request@w3.org
Message-ID: <OF6DD0621B.E74EA579-ONC1256CB0.005B80DC-C1256CB0.005BF128@agfa.be>


but
:Jenny :age "11"
does not entail
:Jenny :age "11"^^xsd:string
nor does the latter entail the former

-- ,
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/


                                                                                                                        
                    "Peter F.                                                                                           
                    Patel-Schneider"          To:     w3c-rdfcore-wg@w3.org                                             
                    <pfps@research.bell       cc:                                                                       
                    -labs.com>                Subject:     RE: Type of (the denotation of) a plain literal              
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                    w3c-rdfcore-wg-requ                                                                                 
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                    2003-01-16 12:15 PM                                                                                 
                                                                                                                        
                                                                                                                        





>
>
>> (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 11:44:40 EST

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