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Re: [ENT] Review comments on the SPARQL 1.1. Entailment regime document

From: Ivan Herman <ivan@w3.org>
Date: Tue, 18 May 2010 13:30:50 +0200
Cc: Chimezie Ogbuji <ogbujic@ccf.org>, Axel Polleres <axel.polleres@deri.org>, Sandro Hawke <sandro@w3.org>, W3C SPARQL WG <public-rdf-dawg@w3.org>
Message-Id: <F42D20AC-2209-4F89-AC29-71EFD82866E0@w3.org>
To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>

On May 18, 2010, at 13:17 , Birte Glimm wrote:

> [snip]
>> I am o.k. with the content but not being moved into 5.1. The whole section refers to OWL, uses the functional syntax, etc, etc, ie, it belongs to the OWL section.
>> 
>> Of course... I guess the issue is that the content is also valid for the RDF based semantics of OWL and not only to DL. So the right place would be to place it there, instead of the OWL DL. The only caveat is that the functional syntax is still DL specific. A solution would be to remove the FSS expressions altogether (sorry...) and then place it to the OWL Full part.
> 
> I removed the FSS now because the OWL 2 RDF-Based regime is the first
> where this kind of problems arise, so it should be discussed there. In
> the OWL 2 Direct Semantics I now state that without C2 infinite
> answers can come from datatype reasoning and I link to the example in
> the RDF-Based Semantics regime.
> 
> I also tried to set up the script that the OWL WG used to make it
> possible to select in the beginning which syntax you want to see and
> then all examples are displayed in the chosen syntax. Unfortunately I
> couldn't get it to work in XML because we edit XML documents that are
> then compiled into HTML documents. If it is not working in XML, it
> makes it really hard to check whether all is ok since I don't want to
> compile into HTML all the time. I guess the OWL DL folks just have to
> live with Turtle for this one example ;-)
> 

I think they will survive:-)

Ivan

> As far as I am aware, this is the last issue for the non-RIF sections,
> but I hope I don't miss anything.
> 
> Birte
> 
>>> 
>>> [snip a RIF comment]
>>> 
>>>> -----------
>>>> Section 7.1
>>>> 
>>>> I also have an issue with the way rif:imports is defined. The text says that the _Graph_ should contain the predicate rdf:imports. This means, if my understanding is correct, that I cannot use that in the query, ie, I cannot have a query that says
>>>> 
>>>> SELECT *
>>>> WHERE {
>>>>   [] rdf:imports <...pathtoruleset...>
>>>>   ... all kinds of patterns
>>>> }
>>>> 
>>>> In other words, I cannot dynamically assign rule sets to the dataset. For a user this looks like a serious restriction because that means that the dataset provider dictates the rule sets it has, rather than the user.
>>>> 
>>>> Isn't it possible to say that the rdf:imports can also be part of the BGP and has, well, the same semantics of referring to a rule set?
>>>> 
>>>> Actually, the same question applies to various OWL regimes, too. Can I have a [] owl:imports <...> in my BGP? Should we allow this?
>>> 
>>> I think we have discussed this already before and the BGP is really
>>> not the place where these things should go IMO. A BGP just tests
>>> something, either whether the triples match to the queried graph or
>>> whether they are entailed by the queried graph. Even if you have a BGP
>>> such as
>>> { [] owl:imports ?x }
>>> the only natural interpretation is to consider that as a query that
>>> asks whether the queried graph contains an import statement. In OWL
>>> RDF-Based Semantics, you would get the IRIs of the imported ontologies
>>> back because these triples are just normal triples under RDF-Based
>>> Semantics. Under Direct Semantics you wouldn't get an answer because
>>> such triples are non-logical and not entailed no matter which binding
>>> you try.
>>> 
>>> What you can do in any regime is to create a new default graph that
>>> contains the triples from all documents in the FROM part of the query.
>>> E.g.,
>>> SELECT ?x FROM IRI_1, IRI_2 WHERE { ?x ex:p ex:o }
>>> uses the triples from both IRI_1 and IRI_2 to find the answers with
>>> whatever ent. reg. is being used.
>> 
>> Ah! Right. I think this is, technically, a way to go.
>> 
>> Maybe an example for that somewhere in the text would help idiots like me...
>> 
>> Thanks!
>> 
>> 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


----
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







Received on Tuesday, 18 May 2010 11:30:21 GMT

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