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

From: Axel Polleres <axel.polleres@deri.org>
Date: Thu, 8 Oct 2009 14:42:09 +0100
Cc: "SPARQL Working Group" <public-rdf-dawg@w3.org>, "Ivan Herman" <ivan@w3.org>, "Andy Seaborne" <andy.seaborne@hp.com>
Message-Id: <A2F0E2A2-5F5C-41E3-A463-344D36548F55@deri.org>
To: "Birte Glimm" <birte.glimm@comlab.ox.ac.uk>

On 8 Oct 2009, at 14:38, Birte Glimm wrote:

> 2009/10/8 Axel Polleres <axel.polleres@deri.org>:
> > p.s.: the proper URL for the references should have been:
> >
> > 1. http://www.w3.org/TR/rif-rdf-owl/#Importing_RDF_and_OWL_in_RIF
> >
> > Also, FWIW, RIF has already defined some URIs for entailment  
> regimes, we may
> > think about adopting those,
> > cf.  http://www.w3.org/TR/rif-rdf-owl/#Specific_Profiles
>
> Hm, I am not sure I would like IRIs with rif-import-profile for SPARQL
> entailment regimes.
>
> http://www.w3.org/2007/rif-import-profile#RDFS
> Ordo you mean to just use the names such as RDFS, Simple, OWL-DL?
>
I think we should have full URIs to identify those, what speaks  
against reusing the RIF ones?
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)

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
>
Received on Thursday, 8 October 2009 13:42:45 GMT

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