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

Hey Chime,

Quick reply. Unfortunately, I cannot be on the call; I am on my way to Sweden...

On May 17, 2010, at 21:20 , Chimezie Ogbuji wrote:

> Thanks for the review Ivan, see responses below for those comments referring
> to my sections.
> 
> On 5/12/10 11:04 AM, "Ivan Herman" <ivan@w3.org> wrote:
>> -----------
>> Section 7
>> 
>> At the moment, the http://www.w3.org/ns/entailment/ vocabulary does _not_
>> include the
>> 
>> http://www.w3.org/ns/entailment/RIF-RDF-Strongly-Safe-Core
>> 
>> but only
>> 
>> http://www.w3.org/ns/entailment/RIF
>> 
>> It is easy for me to add this additional URI, but I have to be sure this is
>> o.k. with the RIF group, and whether it is the correct name. And, if I add
>> this, shouldn't I add others? Which ones? Axel, Sandro, can you help on that?
> 
> Ok, I'll leave that one as is until there is further input

I leave that to Axel and Sandro


> 
>> -----------
>> Section 7.1
>> 
>> I think we have a pending issue as for which namespace rif:imports is in. The
>> current text does not specifies this at all. There should be a namespace
>> document, too.
> 
> I have explicitly designated the following namespace URI:
> 
> 
>            http://www.w3.org/ns/entailment/RDF-RIF-imports
> 
> I'm not sure who is responsible for setting up the namespace document, but
> text from this section should be sufficient for the body of such a document.

I am the one maintaining these and Sandro can also do it. That being said, I am not sure that is the right place to do this. The .../entailment/XXX URI-s are used designate specific entailment regimes, and this is something different.

Ideally, this predicate should be in the rif namespace, but that would require, I presume, an agreement from the RIF group (that again falls into the domain of Sandro and Axel, I am afraid). We may have to mint a URI of its own, which looks a bit silly....

> 
>> -----------
>> Section 7.1
>> 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?
> 
> Per the thread with you and Birte on this, I have not done anything since a
> more fundamental change to the SPARQL syntax would be needed to facilitate
> query-time specification of a ruleset to use (and this was ruled out early).

Well... indeed, Birte convinced me that the current setup is actually fine, and an import can be done via an extra graph that uses the import. That being said, I do not understand your last remark: with the semantics of rif:import one _can_ specify the rule set dynamically at query time (provided the endpoint is capable of reading an RDF file at an external URI). And that is the right thing to have!

[snip]
> 
>> -----------
>> I wonder whether it would be good adding some additional (informal) text in
>> the RIF related text that makes it clear that, although we define the
>> entailment regime only in terms of the RIF-Simple, it is possible to define
>> RIF Core rule sets that describe RDFS and even OWL-RL. Ie, with suitable rule
>> sets, this entailment is much more powerful than it looks at first. A
>> reference to
>> 
>> http://www.w3.org/TR/2010/WD-rif-owl-rl-20100511/
>> 
>> and to ter Horst's paper (which, actually, still appears in the reference
>> list) would be useful.
> 
> I've added a new section: 7.2 Custom Rulesets for Common Vocabulary
> Interpretations (Informative) that discusses this.

Yep! Thanks

Ivan


> 
> -- Chime
> 
> 
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----
Ivan Herman, W3C Semantic Web Activity Lead
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