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Re: [TF-ENT] Entailment Regimes telecon

From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Date: Wed, 4 Nov 2009 11:50:26 +0000
Message-ID: <492f2b0b0911040350xae154dclaf189ba690837fa8@mail.gmail.com>
To: Ivan Herman <ivan@w3.org>
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
>> The doodle poll suggests Friday 13th 14.00-15.00 UK time (15.00-16.00
>> rest of europe, I think tht is 09:00-10:00 EST, Sandro is that where
>> you are?). IRC channel sparql-ent.
>> I hope the dial in numbers are the same as usual...
>
> I am not sure this is fully possible. Rather: I will invite zakim from
> the irc channel and ask for an ad-hoc call. The dial in code will be on
> irc then, or you will be able to say
>
> zakim, code?

ok, Zakim is my friend ;-)

[snip]

>> Issues to discuss:
>>     * [ISSUE 28]: Entailment regimes vs. update?
>> This obviously also relates to update. I am not sure it is compatible
>> with the conditions on extensions to BGP matching, but one way to go
>> would be to always apply simple entailment semantics to update
>> queries. That would be a bit of a burden for OWL Direct Semantics
>> application because you have to implement data structures to keep an
>> RDF graph that you use to do the updates and after each update you
>> have to convert from the triples into the OWL logical constructs.
>> Another option would be to say that update is not yet defined for use
>> with entailment regimes and leave that open to future versions of
>> SPARQL.
>
> I would not be shocked if we say that there is no relation. Ie, that the
> entailment regimes are valid for query only. This could be a way out if
> we feel there are too many mines hidden on this subject. I guess your
> proposal of applying simple entailment semantics to update is more or
> less similar, isn't it?

Well, as I understand it, you consider leaving it undefined, whereas
my suggestion is to treat updates always with simple entailment
semantics, i.e., you delete/modify a triple only if it is matched by
simple entailment and the triple that is to be deleted/modified is
actually in data and not just an inferred triple. So, if you say
DELETE { :something a :D }
and your data has the triples
:something a :C . :C rdfs:subClassOf :D.
your delete would have no effect and if you then query
SELECT ?x WHERE { ?x a :D }
you would still get :something as answer.
Since we want to keep it as simple as possible for now, I would be
happy to say entailment regimes are only valid/defined for query.

Birte

>>     * [ISSUE 34]: How do entailment regimes interaction with
>> aggregates, grouping, and blank nodes?
>> I think that is clear now from the definition of the semantics,
>> although we might have to make it clearer to readers?
>>
>>     * [ISSUE 40]: How can other entailment regimes plug in their
>> semantics to SPARQL/Update?
>> see issue 28
>>
>>     * [ISSUE 42]: TF-ENT What should happen for RDFS entailment in the
>> face of inconsistencies?
>> Are we all happy with the current solution?
>>
>>     * [ISSUE 43]: should entailment-regimes be declared over the whole
>> dataset or individual graphs?
>> This relates to service descriptions as well. Andy is in favour of
>> being able to declare entailment regimes per graph and I am slightly
>> in favour of that too. If the majority thinks so, we should probably
>> asks for an extension in this direction in the service description
>> doc.
>>
>
> Thanks for taking this on Birte!
>
> Ivan
>
>>
>>
>
> --
>
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
>
>



-- 
Dr. Birte Glimm, Room 306
Computing Laboratory
Parks Road
Oxford
OX1 3QD
United Kingdom
+44 (0)1865 283529
Received on Wednesday, 4 November 2009 11:51:07 GMT

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