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Re: Semantics of rdf:value

From: Frank Manola <fmanola@mitre.org>
Date: Fri, 06 Dec 2002 08:56:38 -0500
Message-ID: <3DF0AC96.10703@mitre.org>
To: pat hayes <phayes@ai.uwf.edu>
CC: w3c-rdfcore-wg@w3.org

pat hayes wrote:

>> pat hayes wrote [to Brian]:
>>
>>>
>>> snip
>>> OK, fine. But then I have a new issue, which applies to rdf:value but 
>>> also more generally.
>>>
>>> In cases where the WG has resolved that the model theory provides no 
>>> semantics for a construct in the RDF namespace, I suggest that none 
>>> of our documents, including the Primer, should be written in a way 
>>> that suggests that the construct does have an intended meaning that 
>>> could support any valid inferences. That is, we should be consistent 
>>> about meaning: when things have no meaning but are being kept for 
>>> essentially political reasons, we should say that clearly.
>>>
>>
>>
>> pat hayes wrote [to DanBri]:
>>
>>>
>> snip
>>
>>>  Then they should not be in the language. They can be in user 
>>> ontologies,
>>>  of course, but then its up to said user to describe them to their own
>>>  satisfaction. Seems to me that we have a responsibility to give clear
>>>  specifications for the meanings of the vocabulary we provide, or 
>>> else to
>>>  say clearly that they have no meaning. I'm quite happy to say that
>>>  rdf:value has no meaning; but then I don't want the primer to explain
>>>  this nonexistent meaning in intuitive terms.
>>
>>
>> Pat--
>>
>> What would you like the Primer to say about rdf:value?
> 
> 
> That is has no defined meaning. Or, just not refer to it, or perhaps 
> refer to it only to say that users should not presume that any meaning 
> they use it for will be understood or shared by any other user. In a 
> word, we should be warning them rather than encouraging them.
> 


I'd like a WG decision on this (and also about similar things, like 
rdf:Alt) then.  In particular, coverage of rdf:value was added to the 
Primer at WG direction, and the text has been sitting there for some 
time.  NB:  The text currently says (near the end):

"You need not use rdf:value in these situations, and RDF does not 
associate any particular meaning with it. rdf:value is simply provided 
as a convenience for use in these commonly-occurring situations."

but this may not satisfy Pat's concern.

On a more general note, I'm not a defender of rdf:value, but I will say 
it seems to me that saying nothing, or practically nothing, about some 
of these legacy pieces of syntax (aside from saying they have no 
meaning) is not particularly responsible on the part of the WG.  We owe 
it to newcomers to RDF to explain why stuff is there (people are bound 
to wonder;  it's the WG's job to tell them), and we owe it to those 
already familiar with (and possibly using) RDF to explain any changed 
status.  I think some more straightforwardness about this is needed (and 
not only in the Primer).  Perhaps we need a new document:  "RDF 
Deprecated Vocabulary".

--Frank

-- 
Frank Manola                   The MITRE Corporation
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Received on Friday, 6 December 2002 08:43:20 EST

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