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Re: [TF-ENT] Querying datasets with default plus named graphs

From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Date: Thu, 8 Oct 2009 14:59:37 +0100
Message-ID: <492f2b0b0910080659t4903c656y9cdc4997c2d664ba@mail.gmail.com>
To: Axel Polleres <axel.polleres@deri.org>
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>, Ivan Herman <ivan@w3.org>, Andy Seaborne <andy.seaborne@hp.com>
[snip]
> http://www.w3.org/2007/rif-import-profile#RDFS
> Ordo you mean to just use the names such as RDFS, Simple, OWL-DL?
I meant
http://something/Simple etc, where something is not specific to RIF.

> I think we should have full URIs to identify those, what speaks against
> reusing the RIF ones?

Well, I find it confusing to call a SPARQL entailment regime
rif-import-profile, but it would not kill me if we were to use them,
just I find it not clear.

> At least, it might be nice to have them aligned (I am afraid at this stage
> it might be
> tricky to change them on the RIF side, would need to check, what's the
> opinion on that side as well)

http://www.w3.org/2007/entailment#RDFS
would be less RIF specific, but since RIF is now (candidate?) rec, it
might be too late.
Birte

> best,
> Axel
>
> That's fine for me.
> Birte
>
>> best,
>> Axel
>>
>> On 8 Oct 2009, at 14:05, Axel Polleres wrote:
>>
>>>> > It also raises an issue on the RIF side. RIF rules cannot be expressed
>>>> > in
>>>> > RDF. How would one add RIF rules to an entailement regime if we wanted
>>>> > to
>>>> > cover RIF? It might be a showstopper for that case:-(
>>>>
>>>> In my total RIF naivity, I would assume you can say:
>>>>
>>>> SELECT ?o FROM <http://example.org/myrules.rif> WHERE { :s :p ?o . }
>>>>
>>>
>>> I was thinking that one viable alternative would be viewing RIF rulesets
>>> rather at the
>>> level of *defining* an entailment regimes in their own right,
>>> thus having them more at the level of service descriptions...
>>>
>>> So, one could define say in SD
>>>
>>>  myEndpoint sd:EntailmentRegime sd:rdfs .
>>>
>>>  myEndpoint sd:EntailmentRegime sd:owl .
>>>
>>> or, alternatively:
>>>
>>>   myEndpoint sd:EntailmentRegime
>>> <http://example.org/myCustomEntailmentRules.rif>
>>>
>>> where <http://example.org/myCustomEntailmentRules.rif> points to a RIF
>>> ruleset, describing the supported entailment rules.
>>>
>>> Alternatively, we could also allow to use
>>>
>>> owl:imports to refer to RIF rulesets (just as RIF allows in its own
>>> imports directive to refer to OWL ontologies, cf. [1]
>>>
>>> Axel
>>>
>>> 1. http://www.w3.org/2005/rules/wiki/SWC#Importing_RDF_and_OWL_in_RIF
>>>
>>>
>>> On 8 Oct 2009, at 11:34, Birte Glimm wrote:
>>>
>>>> 2009/10/8 Ivan Herman <ivan@w3.org>:
>>>> >
>>>> > Axel Polleres wrote:
>>>> [snip]
>>>> >> +1 to keep entailments local to the separate  graphs in the DS
>>>> >> (<chairhatoff> although  I  personally consider it a drawback that
>>>> >> you
>>>> >> can't refer to ontologies from named graphs)
>>>> >
>>>> > Hm. Yes, this seems to be a consequence which is a bit disagreeable
>>>> > indeed:-(
>>>> >
>>>> > In OWL, I can of course use owl:import in my WHERE clause (Birte, this
>>>> > is
>>>> > all right, isn't it?) which is not that bad, the user has to make
>>>> > things
>>>> > explicit. But this does not help the RDFS case.
>>>>
>>>> In OWL you can use imports, but I suppose you mean FROM and not WHERE
>>>> clause. If the ontology you are querying (as given in the FROM (NAMED)
>>>> clause) contains imports, then all imports will be loaded and the
>>>> axioms from the imported ontologies will be taken into account for
>>>> finding the query answers.
>>>>
>>>> > It also raises an issue on the RIF side. RIF rules cannot be expressed
>>>> > in
>>>> > RDF. How would one add RIF rules to an entailement regime if we wanted
>>>> > to
>>>> > cover RIF? It might be a showstopper for that case:-(
>>>>
>>>> In my total RIF naivity, I would assume you can say:
>>>>
>>>> SELECT ?o FROM <http://example.org/myrules.rif> WHERE { :s :p ?o . }
>>>>
>>>> Here I assume that myrules.rif contains the rules and references
>>>> (imports) for the relevant RDF graphs. In the RIF OWL compatibility
>>>> doc it says:
>>>>
>>>> A RIF document that refers to (imports) RDF graphs and/or RDFS/OWL
>>>> ontologies, or any use of a RIF document with RDF graphs, is viewed as
>>>> a combination of a document and a number of graphs and ontologies.
>>>> This document specifies how, in such a combination, the document and
>>>> the graphs and ontologies interoperate in a technical sense, i.e., the
>>>> conditions under which the combination is satisfiable (i.e.,
>>>> consistent), as well as the entailments (i.e., logical consequences)
>>>> of the combination. The interaction between RIF and RDF/OWL is
>>>> realized by connecting the model theory of RIF [RIF-BLD] with the
>>>> model theories of RDF [RDF-Semantics] and OWL [OWL2-Semantics],
>>>> respectively.
>>>>
>>>> In my example, I assume that myrules.rif is such a document as
>>>> mentioned above and you would query the RDF graphs pls the entailmens
>>>> that you get from the rules.
>>>>
>>>> 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
>>>>
>>>
>>
>>
>
>
>
> --
> Dr. Birte Glimm, Room 306
> Computing Laboratory
> Parks Road
> Oxford
> OX1 3QD
> United Kingdom
> +44 (0)1865 283529
>
>



-- 
Dr. Birte Glimm, Room 306
Computing Laboratory
Parks Road
Oxford
OX1 3QD
United Kingdom
+44 (0)1865 283529
Received on Thursday, 8 October 2009 14:00:13 GMT

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