RE: [ALL] RDF Data Access, XQuery, rules

> However, the practical difficulties with OWL, since it is on
> the limit of terminating and complete tractability, mean that in
> practice there will be more implementation variability than in DAWG
> without inference.
>

I can't agree with you more.

Having said that, the practical issues with OWL does not affect the
query language design in this case. As it is a one size fit all. Just
that finding the right engine to give you the right result is a little
tricky when there is no guarantee what you are going to get... feel
sorry for those using OWL Full. DL is hard enough :)

G

> -----Original Message-----
> From: Jeremy Carroll [mailto:jjc@hplb.hpl.hp.com]
> Sent: 30 September 2004 03:05
> To: Gary Ng
> Cc: public-swbp-wg@w3.org
> Subject: Re: [ALL] RDF Data Access, XQuery, rules
> 
> 
> I noted in today's agenda:
> [[
> 6.  Comments to DAWG on RDF Data Access, XQuery, Rules
> 
>      [ALL] RDF Data Access, XQuery, rules
>
http://lists.w3.org/Archives/Public/public-swbp-wg/2004Sep/0049.html
> 
>      Any volunteers for a second reviewer?
> ]]
> 
> 
> I've also looked at:
> 
> http://www.w3.org/TR/2004/WD-rdf-dawg-uc-20040802/
> 
> and saw nothing there that I thought needed this WG's attention,
> although I did make a comment about literal matching ... (particularly
> worrying about I18N issues)
> 
> http://lists.w3.org/Archives/Public/public-rdf-dawg-
> comments/2004Sep/0007.html
> 
> 
> In terms of Dan's specific questions:
> 
> 1.
>  > Anybody have experience with XQuery/RDF integration to share?
> 
> No, I was happy with the downplaying of XQuery in this doc.
> I am also happy to see that they are intending to work with XPath
> Functions and Operators, which should mean that they don't drift too
far
> from the XQuery view of the world.
> 
> Gary's
>  >   If either the above answers is no, or we don't know,
>  >  then we shall not
>  >  offer any views on this item.
> 
> and the lack of response suggests not offering a view on this item
> (perhaps an explicit 'no comment').
> 
> 
> 2.
>  > Any rules/query integration experience to share? Thoughts
> 
> I found the sections in the use cases adequate on this:
> [[
> 
> 4.6 Additional Semantic Information
> It should be possible for knowledge encoded in other semantic
> languages-for example: RDFS, OWL, and SWRL-to affect the results of
> queries executed against RDF graphs.
> 
> 4.6a Additional Semantic Information (variant)
> It should be possible for a query to indicate that the answers should
> take into account knowledge encoded in RDF semantic extensions such as
> RDFS, OWL, etc.
> 
> Status: Pending.
> 
> ]]
> 
> Yes - the Jena team allow this, as described in:
> http://www.hpl.hp.com/techreports/2003/HPL-2003-146.html
> 
> We have our rule systems set up as graph-to-graph transforms, doing
e.g.
> RDFS or OWL inference.
> The RDQL query lanaguage can then be used to query either the base
graph
> (without inference) or the virtual graph (with inference). Both are
> useful.
> 
> Particularly problem with OWL is that the virtual graph is infinite,
> that can sometimes be surprising.
> 
> Gary says:
>  >   From a development and deployment point of view I think it
>  > makes a lot of sense to be able to use a single query language
>  > across different inferencing system to access instance data.
>  > The choice is then to match inferencing capability to the
>  > expressive that the problem demands.
> 
> I agree. However, the practical difficulties with OWL, since it is on
> the limit of terminating and complete tractability, mean that in
> practice there will be more implementation variability than in DAWG
> without inference.
> 
> Jeremy
>

Received on Thursday, 30 September 2004 10:26:58 UTC