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Re: Comments on this afternoon session on Turtle

From: Peter Frederick Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 14 Apr 2011 08:09:22 -0400
Message-ID: <20110414.080922.1517189823041986055.pfps@research.bell-labs.com>
To: <lee@thefigtrees.net>
CC: <antoine.zimmermann@insa-lyon.fr>, <antoine.zimmermann@deri.org>, <public-rdf-wg@w3.org>
From: Lee Feigenbaum <lee@thefigtrees.net>
Subject: Re: Comments on this afternoon session on Turtle
Date: Thu, 14 Apr 2011 06:25:27 -0500

> On 4/14/2011 3:47 AM, Antoine Zimmermann wrote:
>> Just a comment and what my votes would have been if I could have joined
>> the session.
>>
>> ========
>> PROPOSED: Mark xs:string as archaic for use in RDF, recommending use of
>> plain literals instead. Recommend that systems silently convert
>> xs:string data to plain literals.
>>
>> -1
>>
>> I always thought of plain literals as a written utterance in an
>> unspecified language. This is not what xs:strings are. Strings are a
>> sequence of characters, irrespective of any language. They cannot be
>> translated or assigned a language tag. xs:string should be used for
>> things like serial numbers, identifiers, passwords, etc.
>>
>> I would rather have plain literals with no language tags implicitly
>> meaning xs:string (as Jean-Fran├žois proposed but it seemed unnoticed).
>> xs:string is not defined by RDF anyway, I don't know why RDF should
>> reject this particular XML datatype.
>>
>> If plain literals with no lang tag are implicitly typed with xs:string,
>> then all literals have either a datatype or a language tag, which
>> simplifies the manipulation of literals.
> 
> I agree with this point of view.
> 
> Lee

From RDF Semantics:

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".


So, both plain literals and xsd:string datatype literals are finite
sequences of Unicode characters, nothing else.


The qualification above has to do with "illegal" literals, like
"x"^^xsd:integer.  I'm not sure whether there are any "illegal"
xsd:string literals.  



peter
Received on Thursday, 14 April 2011 12:10:21 GMT

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