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Re: Entailment Regimes Doc

From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Date: Wed, 30 Sep 2009 18:56:44 +0100
Message-ID: <492f2b0b0909301056vde18607w1adb44fbad75b9ce@mail.gmail.com>
To: "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
2009/9/30 Steve Harris <steve.harris@garlik.com>:
> I've skimmed the document, and I have some questions and comments.
> 1) I'm sure sure how the scoping graph and active graph related to the rest
> of the document. Linking to the definitions in SPARQL 1.0 might be more
> helpful. I don't find the related section in SPARQL 1.0 especially clear
> either, but it's trying to talk in very general terms.

I'll add links to the according section in the SPARQL 1.0 spec.

> 2) Where it says "Systems who want to support... can state..." is that
> intended to be a requirement for the service description section, or is
> state meant in an informal sense?

Any suggestion whether it should be or not? So far Bijan and I started
by looking at RDFS and RDF and it seems that one can use the same
conditions to meet the requirements that entailment regimes have to
satisfy, so we didn't want to have two more or less duplicate
sections, one for RDF and one for RDFS. We might even use the same
conditions for D-entailment, if it seems they fit well. Now that
obviously does not mean that RDF (and maybe D-entailment) cannot or
should not be proper entailment regimes. It would be a possibility
though. I not much of an opiniomn about it ad I am happy about any
opinions or advice. So far it is more undecided and the sentence
should be rephrased once we know better what we want.

> 3) In the section on RDFS, I share Andy's concerns. My systems wouldn't have
> been able to detect the inconsistent case with acceptable efficiency either.

Ok, we'll work on alternatives/changes. I'll add a note on that now
and we'll see how we can solve this soonish.

> General notes:
> It's not clear to me how the terms used 1) relate to the ground data. I'm
> not really familiar with the mechanics of typical OWL reasoners, so it could
> be obvious to practitioners.

Hm, here I don't know where you are referring to. Is 1) just a one
with no two or is that referring to the scoping graph above, in which
case I am not sure how that relates to ground data. Are you looking at
the (unfinished) OWL section or are you thinking of OWL implementors
as implementors for the RDFS entailment regime?

> Is the implication that inference only happens within a (named) graph?

Good point. I have to check on that and see whether this is clear from
the SPARQL 1.0 spec or whether we have to specify something for that
in the ent. regimes. The notion of named or default graph is not used
in the OWL context. I have never seen it in the RDF(S) spec either
(maybe I forget), so if the SPARQL spec does not say anything, then we
have to address that I guess. Any clues?

> If not, is there an intention to specify what bindings ?g might take in the
> following example:
> <a.rdf>:
>  :p rdfs:domain :A .
> <b.rdf>:
>  :x :p :y .
> query:
>  SELECT ?g WHERE { GRAPH ?g { :x a ?type } }
> - Steve

Thanks for the comment,

> --
> Steve Harris
> Garlik Limited, 2 Sheen Road, Richmond, TW9 1AE, UK
> +44(0)20 8973 2465  http://www.garlik.com/
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Dr. Birte Glimm, Room 306
Computing Laboratory
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United Kingdom
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Received on Wednesday, 30 September 2009 17:57:19 UTC

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