W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > October to December 2009

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

From: Ivan Herman <ivan@w3.org>
Date: Fri, 9 Oct 2009 05:00:48 -0000 (UTC)
Message-ID: <42c727cd822dcc547ca1ee5fea82422b.squirrel@webmail.sophia.w3.org>
To: "Birte Glimm" <birte.glimm@comlab.ox.ac.uk>
Cc: "Axel Polleres" <axel.polleres@deri.org>, "SPARQL Working Group" <public-rdf-dawg@w3.org>, "Ivan Herman" <ivan@w3.org>, "Andy Seaborne" <andy.seaborne@hp.com>
I agree. Even if, theoretically, URI-s are only names and one should not assign
semantics to the english (or other) words appearing in URI-s, the fact of the matter is
that people do. Ie, using URI-s that refer to particular RIF mechanisms will be
confusing for our readers.

Axel, I would not think that changing those URI-s in RIF would be a major technical
change, so I would not be shocked of getting them changing to some other, less RIF
specific URI-s even in CR phase. But that something that the RIF group should decide. Do
you think you can do the honour and ask them?

If there are good reasons for RIF not changing those than we should probably mint our
own URI-s...

Ivan



On Thu, October 8, 2009 1:59 pm, Birte Glimm wrote:
> [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
>


-- 
Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Friday, 9 October 2009 05:01:21 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:40 GMT