W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > September 2001

Re: 2001-09-07#5 - literal problem

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Fri, 14 Sep 2001 10:59:14 -0500
Message-Id: <p05101000b7c7be50b6a3@[]>
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Cc: w3c-rdfcore-wg@w3.org
>>  ***the purpose of 'should not' is to allow applications some flexibility
>>  on dealing with language tags. That is, when a literal is equal to
>>  another but only one has a lag tag, they can be considered equivalent,
>>  which might be sufficient for some applications to make a match.
>>  I find this odd. Why not let them be equal in this case? Omitting the
>>  language tag presumably means that no language information is being
>>  supplied. But in that case, there is no need to reject a match with
>>  an identical literal which does have a language tag, is there?
>I agreed with Bill earlier, and continue to do so.
>The purpose of defining equality is that in the model theory we are
>talking about a graph, which is a set of edges. We need to be able to
>tell whether one edge is the same or different from another edge.
>We are not trying to define a processing model for language aware RDF
>I think the graph constructed by
>_:a <rdf:value> ("Roma", "it").
>_:a <rdf:value> ("Rome", "en").
>_:a <rdf:value> ("Rome", "fr").
>_:a <rdf:value> ("Roma", _ ).
>is different from
>_:a <rdf:value> ("Roma", "it").
>_:a <rdf:value> ("Rome", "en").
>_:a <rdf:value> ("Rome", "fr").
>If the literal ( "Roma", _ ), i.e. with no language specified, is the
>same as ("Roma", "it"), i.e. in italian, then the two graphs are
>Now, suppose we have a language aware graphical information system, and
>a user whose preferred language is "fr-ca" (French Canadian) comes up. I
>have quite deliberately not tried to specify which label goes onto the
>big city half way up italy.
>Such an app may be clever enough to decide that "fr" is a better match
>to "fr-ca" than _ but maybe not.
>A different application, may always read a pair ( "string", _ ) using
>the currently set default language; while that certainly should not be
>the default case, I wouldn't want to rule it out as a way of processing

OK, fair enough, and very good points. I guess that I have been 
thinking of the lang attribute as a kind of property, which isn't 
appropriate when we are talking about syntactic identity. So I 
withdraw my query and suggest that Bill go back to his original 
three-(or maybe 2.5 -)valued truth-table.


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Received on Friday, 14 September 2001 11:59:14 UTC

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