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Re: [TF-ENT] RDFS entailment regime proposal

From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Date: Tue, 29 Sep 2009 11:57:18 +0100
Message-ID: <492f2b0b0909290357v5bb26a6eg23feee5c60cf4788@mail.gmail.com>
To: "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>

>> It is definitey something we should discuss in the telcon if we have
>> the time and if not, I would like to have some more opinions on that
>> and some more explanations of the effects that such a change would
>> have.
>> Birte
> There are implicit assumption on the processing model that would make it hard for a backward chaining engine to work with, say. (They would seem to have to a consistency check as well as answer the query).  I think it's an important to pull out these assumptions and state them - hence the requirements needs.
> (I know there is there's no mention of OWL-RL in the document (although I haven't yet understood that matter)).

It is not yet mentioned. The document is still at a very early stage.
RIF is also not mentioned yet. What is said about OWL is not at all
final. RDFS is at a stage, I would say, where we can discuss what is
suggested, change and extend what is there etc to get to a proper

> The OWL2 conformance spec [1] does not require an OWL2-RL query answering system be based on a consistency checker; even if it is, and the checker returns "unknown" (RDF-Based Semantics), as might be the case if the data is outside theorem PR1, what happens?  So I think we need to deal with similar situations anyway.

I much prefer the wording of the OLW spec using SHOULD instead of MAY
and more or less clearly outline what can happen when regarding
soundness and completeness. IMO that is a way to go. If we use SHOULD
and you have good reasons not to do a consistency check first (because
for your implementation that would have implications on the
performance in the general case that are not justifiable), then this
is a reason not to do it.


>        Andy
> [1] http://www.w3.org/TR/2009/PR-owl2-conformance-20090922/#Query_Answering_Tool

Dr. Birte Glimm, Room 306
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Received on Tuesday, 29 September 2009 10:57:55 UTC

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