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

Re: reification "subagenda"

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Thu, 14 Feb 2002 18:18:03 -0500
Message-Id: <p0510142ab891f3883be2@[192.168.0.6]>
To: Dan Connolly <connolly@w3.org>
Cc: w3c-rdfcore-wg@w3.org
>On Wed, 2002-02-13 at 16:18, Frank Manola wrote:
>[...]
>>  1.  Brian suggests that we (explicitly) decide on answering the
>>  question:  Does
>>
>>     <stmt1> <rdf:type> <rdf:Statement> .
>>     <stmt1> <rdf:subject> <subject> .
>>     <stmt1> <rdf:predicate> <predicate> .
>>     <stmt1> <rdf:object> <object> .
>>
>>     <stmt2> <rdf:type> <rdf:Statement> .
>>     <stmt2> <rdf:subject> <subject> .
>>     <stmt2> <rdf:predicate> <predicate> .
>>     <stmt2> <rdf:object> <object> .
>>
>>     <stmt1> <property> <foo> .
>>
>>     entail:
>>
>>     <stmt2> <property> <foo> .
>>
>>  [Brian suggests that the answer is NO]
>
>I really wrestle with this. The M&S spec is quite clear that
>the answer is YES, as PeterPS has pointed out in
>his message to www-rdf-logic of 04 Feb 2002 13:24:08 -0500.

OK, and I think he is right. But on the other hand the M&S is often 
confused on use/mention issues, and this could plausibly be seen as 
one of those, so maybe that aspect of the M&S can be taken with a 
pinch of salt.

>We don't think that anybody is relying
>on that part of the M&S spec, but I'm pretty uncomfortable
>pulling the rug out from under somebody who *does* rely
>on it, but hasn't followed our recent work.

OK again, but I really don't think that this will pull the rug out. 
At worst it might shake it a little. If someone wants a reification 
to mean the proposition or the 'abstract' triple, and we say it means 
a concrete token of the triple, then all they have to do is to 
re-interpret their properties to mean 'bears the <whatever> relation 
to the *triple/proposition encoded by the inscription*....', where 
the *..* words have to be inserted. This is very similar to what we 
are doing to people who want to write
<mary> <age> "10"
where by insisting that literals ARE strings, we aren't actually 
saying that they can't write triples like that; only that when they 
do, they have to think of <age> as meaning, '...age is the *number 
indicated by the numeral*...' rather than '..age is ...'.

What the 'more particular' interpretation does, in both cases, is to 
force a reification to be more particular: to have more information 
in it, in a sense. You are always free to ignore that extra 
information, however, and use the particular to stand in for the more 
general. But the reverse doesn't work; if we go for the more abstract 
notion, anyone who wants to use it for eg provenance, is screwed.

>We can make up a new design, but I think
>we should use new URIs for the terms in this new design.
>
>I don't want to delay a decision... but in good conscience,
>I may have to vote against this to be sure The Director
>takes a look at it.

Well, by all means, but please make sure that the case is made out to 
him by a good lawyer.

Pat

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Received on Thursday, 14 February 2002 18:18:07 EST

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