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RE: [jena-dev] Re: Use cases for Reification in RDF Triplestores

From: Massimo Marchiori <massimo@w3.org>
Date: Fri, 10 Jan 2003 13:11:48 +0100
To: "Brian McBride" <bwm@hplb.hpl.hp.com>, "Bob MacGregor" <macgregor@ISI.EDU>, <seth@robustai.net>, "Dave Reynolds" <der@hplb.hpl.hp.com>
Cc: <www-rdf-comments@w3.org>, <www-rdf-interest@w3.org>
Message-ID: <NGBBJNKIMLOPPCFHEJEMOEGPDBAA.massimo@w3.org>

Contravening to the first rule "read all the RDF specs 101% before speaking", which I didn't have time to do, a quick interjection:
I found the whole discussion rather confusing, in that I don't see any problem with the way the wg acted with reification. But maybe
I'm just not getting the core of the issue so pls somebody elucidate me if I'm wrong.
I've always been one of the n.1 defenders of reification, and from what I see, "support for reification" is exactly the same as it
was in the pre-MT era: the possibility to reify is there (syntactically in the graph), but there's no semantics for it (yet).
And this seems a perfectly reasonable choice: of course reifications can have lot of uses, but they all go beyond first order logic
(and its easy neighbours). So the moment RDF core decided to put in place some minimal semantics ("first-order like", so to say),
reification just stays out from the semantic rules.
I had built an alternate (= different from the current MT) first-order semantics for RDF back in 1999, and even there, although I
like reification a lot (and, exactly like Bob, see lot of uses for it), for the sake of simplicity I just left reification out of
the primary semantics, exactly like RDF-core is doing now.

So again, where's the problem? The current MT gives a basic first-order-like semantics. Possible semantic rules for reification are
higher-order (or better, just say "meta").
Ergo, these rules just stay out of this basic RDF MT semantics.
The important thing is, when someone (or rdf-logic in the future) will like to build more sophisticated tool, they could take
reification and put some semantic rule for it.
But doing it now would go against the 80/20 rule, and make a basic semantics just too complex for the added value.
No? Is here something new that I am missing (see 101% above ;) ?

Thanks,
-M

> -----Original Message-----
> From: www-rdf-comments-request@w3.org
> [mailto:www-rdf-comments-request@w3.org]On Behalf Of Brian McBride
> Sent: Friday, January 10, 2003 10:39 AM
> To: Bob MacGregor; seth@robustai.net; Dave Reynolds
> Cc: www-rdf-comments@w3.org; www-rdf-interest@w3.org
> Subject: Re: [jena-dev] Re: Use cases for Reification in RDF
> Triplestores
>
>
>
> Hi Bob,
>
> With Pat leading the technical discussion, I'm just going to drop in a
> couple of minor process points here.
>
> At 13:41 09/01/2003 -0800, Bob MacGregor wrote:
>
> [...]
>
> >>Yes, the WG has decided, nodes of rdf:type rdf:Statement *are* statings,
> >>I think you guys should accept that and move on.
> >
> >I apologize for my ignorance on WG decisions; I missed this particular
> >one.  I would appreciate someone mailing me a pointer to the published
> >decision.
>
> As a general rule, resolution of WG issues can be found from the WG Issues
> document.  In this case the URL to appropriate section of that doc is:
>
>    http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-of-statements
>
> There is also another issue which may be related to your concerns, that the
> WG postponed for consideration by a future WG:
>
>    http://www.w3.org/2000/03/rdf-tracking/#rdfms-contexts
>
> The WG is now (I hope) very close to publishing its last call
> documents.  If you remain unconvinced about the WG's decision, I suggest
> you make this comment again as a last call comment.  The WG will consider
> that comment and any support it receives.
>
> A couple of other remarks:
>
>    o there are two concepts - statements and statings and only one bit of
> vocabulary.  The WG, for reasons that Pat has explained picked one for the
> existing vocabulary, and as Pat also mentioned,  that does not preclude
> you, or anyone else, from defining new vocabulary for the missing
> concept.  That is the sort of thing that could be worked out in the
> interest group, and possibly published as a W3C note.
>
>    o I have an association with the Jena project, and being careful to keep
> my role in the WG distinct, I do know that the current Jena implementation
> of reification is an engineering compromise designed to meet the pragmatic
> needs of users.  As WG co-chair, I'd encourage you to work with tool
> developers to explore how to meet your needs.  Such practical experience
> will be invaluable input to a future WG considering the postponed issue.
>
> Brian
>
Received on Friday, 10 January 2003 07:13:33 GMT

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