W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > March 2003

Re: summary of reification semantics issues (material for discussion).

From: Tim Berners-Lee <timbl@w3.org>
Date: Tue, 25 Mar 2003 08:54:54 -0500
Cc: Pat Hayes <phayes@ai.uwf.edu>, w3c-rdfcore-wg@w3.org
To: Dan Connolly <connolly@w3.org>
Message-Id: <5BA87AF6-5EC9-11D7-BCE4-000393914268@w3.org>


On Thursday, Mar 13, 2003, at 00:51 US/Eastern, Dan Connolly wrote:

> On Wed, 2003-03-12 at 15:54, Tim Berners-Lee wrote:
>> Thank you Pat for this summary.  I find in it
>> a conclusion that de-re semantics for reification are useful,
>> which is not the conclusion to which I come.
>
> I don't think they're useful either; but I don't think
> that's all that relevant to the WG's position.
>
> The fact of the matter is: there's deployed code that
> handles reifictation syntax, and it can only be
> reconciled with the de-re semantics.

I would be interested to see how this feature is used in practice
(use scenarios rather than abstract test cases)
It would help me figure out what it was actually used to mean.
Brian had some leads but I've yet to find someone who actually
processes the data and uses the semantics.

> cf
>
> 2.17 Reifying Statements - rdf:bagID and rdf:ID
> http://www.w3.org/TR/rdf-syntax-grammar/#section-Syntax-reifying
>
> in particular,
>   http://www.w3.org/TR/rdf-syntax-grammar/example20.rdf
> and
>   http://www.w3.org/TR/rdf-syntax-grammar/example20.nt
>
>
> we have
>
>   <http://example.org/> <http://example.org/stuff/1.0/prop> "blah" .
>
> and its reification includes
>
>   <http://example.org/triples/#triple1>
> <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject>
> <http://example.org/> .
>
> by analogy...
>
> [...]
>
>>   This can be dramatized by asking: is the
>>> rdf:subject of the triple
>>>
>>> ex:Mary ex:had ex:littleLamb .
>>>
>>> a girl or a uriref  ?
>
> ... this says that the rdf:subject is a girl; i.e.
>
> 	<#marySentence> rdf:subject ex:Mary.
>
> no quoting around ex:Mary there. :-{
>
> That's the way (all?) the deployed RDF parsers work.
>
>
> The WG considered 3 options:
>
>   (a) write a spec for the way the deployed code works
>   (b) write a de dicto spec, and try to get that deployed
>   (c) punt
>
> and we chose (a). I argued for (c) or (b), but we ultimately
> chose (a). I abstained.
>
> Or at least... that's the way I remember it; I can't
> seem to confirm from the records.
>
> We have
>    ACTION: 2002-01-11#3: bwm - check that reification is listed as an
> 	issue ("fix/drop reification")
>    http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0095.html
> but I can't find that issue in the issues list.
>
> It was item 8 on a subsequent agenda...
>
>   RDFCore WG minutes for the Telecon 2002-02-01
>   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Feb/0010.html
>
> ... and here's Jan's re-statment of the 3 options, which made
> it clear that the quoting issues in the de dicto style were
> tricker than they looked...
>
>   Proposals? Re: use/mention and reification
>   From: Jan Grant (Jan.Grant@bristol.ac.uk)
>   Date: Thu, Jan 24 2002
>   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0236.html
>
> but I can't find any actual decision on the matter. Odd.
> Aha! Those long action ids are golden... googling yields...
>
>   http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Jan/0100.html
>   ==>
>   http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-of-statements
>
> ... which is a closely related issue, but it's not
> an issue about de re vs. de dicto per se, as per
> the options in Jan G's message.
>
> So it looks like the WG never decided to adopt the de re
> semantics as opposed to de dicto; the spec just ended
> up de re as clarification of status quo.

Hmmm.  A well-researched historical explanation of the situation.

> -- 
> Dan Connolly, W3C http://www.w3.org/People/Connolly/
>
Received on Tuesday, 25 March 2003 08:54:53 EST

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:56:15 EDT