W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > December 2002

Re: Quick review of RDF primer

From: pat hayes <phayes@ai.uwf.edu>
Date: Sun, 1 Dec 2002 00:07:34 -0600
Message-Id: <p05111b04ba0f52f13337@[10.0.100.247]>
To: Graham Klyne <GK@NineByNine.org>
Cc: w3c-rdfcore-wg@w3.org

>
>General comment, not specifically Primer:  the description of 
>rdf:value is fine, but how does it relate to a normative 
>specification?  What can we say formally about rdf:value?

Right now, we say explicitly that it has no particular meaning.

>What formal semantics (interpretation) allows us to make inferences like:
>
>    my:cat rdf:type ex:DomesticCat .
>    my:cat ex:weight _:x .
>    _:x rdf:value "15" .
>    _:x ex:unit ex:Kilogram
>
>=>
>
>    my:cat rdf:type ex:Obese .

Nothing in the MT provides any connection in meaning between the 
third and fourth triple of the first graph.

I was under the impression that we had formally decided NOT to 
support this kind of usage. Wasn't that part of the local-datatyping 
no-fancy-idioms decision?

>but NOT:
>
>    my:cat rdf:type ex:DomesticCat .
>    my:cat ex:weight _:x .
>    _:x rdf:value "15" .
>    _:x ex:unit ex:Pound
>
>=>
>
>    my:cat rdf:type ex:Obese .
>
>?
>
>My point here is if we are to encourage such usage of rdf:value, 
>then there ought to be some normative description to back up such 
>usage.

I agree.  Either we should not mention this stuff, or else we should 
back it up with some semantics. It wouldn't be hard to do and it 
would also enable us to do some neat datatyping  entailments that 
people seem to think are obvious, such as (with appropriate 
wellformedness caveats)

aaa ppp "sss"^^ddd .

-->

aaa ppp _:x .
_:x rdf:value "sss" .
_:x rdf:type ddd .

Pat

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Received on Tuesday, 3 December 2002 10:58:52 EST

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