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

Re: handling rdf:value

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 9 Dec 2002 10:35:17 -0600
Message-Id: <p05111b19ba1a752b94b0@[10.0.100.86]>
To: Graham Klyne <GK@NineByNine.org>
Cc: w3c-rdfcore-wg@w3.org

>At 10:59 PM 12/8/02 -0600, pat hayes wrote:
>>If people like this idea than it could be captured formally as a 
>>RDF semantic condition corresponding to the inference rule:
>>
>>aaa ppp bbb .
>>bbb rdf:value ccc .
>>-->
>>aaa ppp ccc .
>>
>>for any property ppp. This would fit very naturally into 
>>rdf-entailment. But as this goes beyond 
>>http://www.w3.org/2000/03/rdf-tracking/#rdfms-replace-value.
>>I hereby REQUEST feedback from the WG before inserting it into the 
>>MT. If people think it should be there then I can put it in one 
>>evening this week. All the proofs and so on are transparent to this 
>>addition.
>
>So, if rdf:value is used *without* mentioning the other property we 
>might infer the existence of *some* property that fills that role? 
>e.g.
>
>   bbb rdf:value ccc .
>   -->
>   aaa ppp ccc .
>
>for some ppp?

That might be a bit dangerous to state formally, if ppp has to be 
different from rdf:value, since it amounts to an existential over 
properties. I don't think we need to go there formally, though 
intutitely that is clearly what is often menat, though see Patrick's 
scoping example.

The real lowdown is that rdf:value is *almost* equality, although 
sometimes its *almost* a kind of inverse of the denotation 
relationship (a rdf:value b  iff b denotes a) ; and its hard to pin 
down its meaning in isolation. But if we see it as a kind of adjunct 
- when used with ppp it requires ppp to allow a binary abbreviation - 
then we wriggle out of having to say what it is that rdf:value 
actually means by itself.

>
>#g
>--
>
>(Who is vaguely concerned that this may be trying to achieve more 
>than time permits.   Is there a *minimum* we can say while leaving a 
>crack open for this kind of refinement at a later date?)
>

The *minimum* is probably nothing (in the MT, that is.)

I agree doing things this late is a worry, even small things.  I 
would have done it earlier but I thought we had gotten rid of 
rdf:value. Tell you what, I'll write the section up today (evening) 
and let y'all read it, it will only be a few paragraphs, no great 
loss if we vote it down.

Pat


>-------------------
>Graham Klyne
><GK@NineByNine.org>


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Received on Monday, 9 December 2002 11:35:39 EST

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