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Re: Values and rdf:value

From: Thomas Baker <baker@sub.uni-goettingen.de>
Date: Fri, 9 Jan 2009 10:03:47 +0100
To: Antoine Isaac <aisaac@few.vu.nl>
Cc: Thomas Baker <baker@sub.uni-goettingen.de>, Ivan Herman <ivan@w3.org>, SWD Working Group <public-swd-wg@w3.org>
Message-ID: <20090109090347.GA1124@octavius>

On Thu, Jan 08, 2009 at 07:19:28PM +0100, Antoine Isaac wrote:
> Sorry, it was difficult to resist coining an example as my two cents:
> 
> ex:sun ex:volume ex:sunDiameterKM .
> ex:sunDiameterKM rdf:value "1392000000" ;
>   ex:unit "m"
> 
> In that case, we have a diameter (expected to be called in language a 
> "value") which is complex: it has two facets, the raw "value" (confusing, 
> but how to name it differently?) and the unit.
> 
> Now, I can imagine that someone may actually want to decompose the value 
> itself to fit another standard way of representing it, but keeping the same 
> value-unit pattern:
> 
> ex:sun ex:volume ex:sunDiameterKM2 .
> ex:sunDiameterKM2 rdf:value [ ex:coefficient "1.392" ; ex:exponent "9" . ] ;
>   ex:unit "m"
> 
> The latter example has an rdf:value which is a non-literal RDF node...
> Granted, it's not a nice example, and there might be ways now to do it in a 
> much nicer way. But I guess at the beginning of RDF some people may have 
> judged useful to anticipate that kind of practice.

Some relevant history [1]:

    Issue rdfms-replace-value: Suggestion that the rdf:value property be replaced by rdf:toString.

    Raised Sat, 17 Feb 2001 by Dan Connolly

    Summary: The property rdf:value is used confusingly
    and inconsistently throughout the M&S and is never
    defined. Some have suggested it is used for multi-valued
    properties (some suggest currying is a better way to do
    this) and others have claimed it is for defining the
    lexical representation of a resource. It is requested
    that the Working Group clarify its meaning and usage.

    Resolution: This issue was discussed by the RDFCore WG
    on 11 January 2002 which resolved:

        o resolves to not change the name of this property at this time on the grounds:
            - insufficient reasons to make this change
            - will cause existing uses to be illegal - such as examples in m&s
        o resolves to recast this issue as a need to clarify the semantics of rdf:value.

    At the February 2002 face to face meeting, the RDFCore WG resolved:

       * that rdf:value is a property defined in the RDF namespace
       * that the model theory state that rdf:value is a property
       * that no other model theory semantics is defined specifically for it
       * the issue be closed.

    Currently: Closed (response)

[1] http://www.w3.org/2000/03/rdf-tracking/#rdfms-replace-value

> >For the sentence in question, Alistair points out that we
> >can side-step the issue by just defining RDF plain literal,
> >full stop [1].  
> >
> >If the RDF Primer is telling a somewhat different story
> >from SKOS Primer it would be good to recognize this clearly
> >because readers of the latter may refer back to the former.
> 
> Until now I don't think the documents are really saying really different 
> things. In fact the Primer does not use rdf:value and "value" not very 
> often...

I think rdf:value and the meaning of "value" in an RDF context
are separate (though related) issues.  Where do we stand with
regard to the the sentence referring to "structured RDF value"?

[1] http://lists.w3.org/Archives/Public/public-swd-wg/2009Jan/0027.html

> Actually it is used now once in a possibly confusing way, in 4.6
> >The value of the literal is the notation itself
> I propose to replace it by "The lexical form of the literal is the notation 
> itself"

Good.

Tom

-- 
Tom Baker <tbaker@tbaker.de>
Received on Friday, 9 January 2009 09:04:28 GMT

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