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Re: Review of Entailment Regimes (Action-317)

From: Ivan Herman <ivan@w3.org>
Date: Sun, 3 Oct 2010 10:21:04 +0200
Cc: Chimezie Ogbuji <ogbujic@ccf.org>, Olivier Corby <Olivier.Corby@sophia.inria.fr>, SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <18A115D7-5D94-4C9F-9173-AA21E83B0536@w3.org>
To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Hi Birte, 

On Oct 2, 2010, at 20:01 , Birte Glimm wrote:
> 
>> Comments on your comments, too:
>> 
>> [snip]
>> 
>>> - At the end of Section 2.2 I added an editorial note, which suggests
>>> an alternative C2 condition that basically forbits terms of the form
>>> rdf:_n as bindings. I am a bi concerned that if you want to implemen
>>> the regime via a set of materialisation rules, then at the moment, you
>>> have to look for which n the terms rdf:_n occur in the graph and for
>>> all those you add the axiomatic triples. This seems hard to do with a
>>> set of pre-defined rules that is independent of the input. If you
>>> would use the alternative, materialisation rules do not have to care
>>> for which n a term rdf:_n occurs in the input. I think it might be
>>> useful to point this out and maybe get some feedback from implementors.
>> 
>> Yes, I understand the difficulty, having done some experimental rule based implementation of Horst myself some time ago. Indeed, the engine has to have a special branch that, for example, looks at the maximum 'n' for rdf:_n (Horst's condition was a bit more liberal than what we have). But I am, nevertheless, a bit wary about this alternative because, to use the example in the document, the user's expectation would clearly be to get rdf:_n back as an rdf:Property. I am not sure we should optimize on the implementation here (clearly, it _can_ done by an implementation, it is just a pain in the neck...)
> 
> I also think that the current condition is nicer and I would like to
> keep it, but I am a bit concerned that this might not be what people
> actually implement, so I think asking for feedback could help us to
> judge whether we suggest something that just won't be accepted out in
> the wild.
> 

And I agree with that. But maybe add a note to the note that we are looking, primarily, to the feedbacks from implementers.

Ivan

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Received on Sunday, 3 October 2010 08:17:27 GMT

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