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Re: Parameterized Inference - starting mail discussion

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Thu, 09 Apr 2009 21:42:45 -0400
To: "Bijan Parsia" <bparsia@cs.man.ac.uk>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>
Message-ID: <C6041C55.944D%ogbujic@ccf.org>
On 4/8/09 11:44 AM, "Bijan Parsia" <bparsia@cs.man.ac.uk> wrote:
> On 8 Apr 2009, at 16:01, Axel Polleres wrote:
> [snip]
> This seems to confuse several things:
> 
> 1) the semantics of the BGP (not your 1 I think.)

The semantics of the BGP would be an extension via an entailment regime (
RIF-RDF combinations of OWL DLP).  The well-formed graphs are the ones that
can be embedded in RIF documents.  Model theory can be used to say what the
answers should be (not how to get them).  It would be nice if fully
expressive OWL-DL (like the abstract syntax described in SPARQL-DL) were
used to extend SPARQL at the same time we extend it for RIF "embeddings"

> 2) what gets into the BGP (your 2)

Arbitrary BGPs (but with no bnodes in queries, for a start).  Or the
abstract syntax described in SPARQL-DL, even.

> 3) how one says what the semantics are (and what gets in) (not your 3)

An OWL-DL model theory can be used to govern the semantics ( or the models
of RIF documents embedded with OWL-DLP and RDF ).

> For 2, I'm not quite sure how this differs from any other (named)
> graph manipulation. Take two graphs (DATA and RULES). (I guess I'm
> presuming an RDF syntax for the RULES in this example). The key
> question is whether Answers(Query, DATA union RULES) is the same as
> (Answers(Query, DATA) union Answers(Query, DATA)).
> 
> For the case of RDF encoded rules, under the standard sparql
> entailment regime, I believe these will be equal. Under, say, a RIF
> entailment regime, they probably wouldn't be.

A RIF/OWL entailment extension of SPARQL?

> A) We need a way to name entailment regimes (either a fixed list, or
> extensible)

Some simple, URI-based registry of regimes with well-defined entailment
relationships that are well-formed.  We probably can't deal with Bnodes in
every case.

> B) We need to trigger entailment regimes in a query
> (Lots of issues there, e.g., only for the whole query, or settable
> on a graph by graph basis; or over sets of graphs, or their merge).

Just for the query.

> Is there anything else, conceptually speaking, in the idea of
> Parameterized Inference per se?

I can't think of anything else.
 
----------------------
Chimezie Thomas-Ogbuji
Heart and Vascular Institute (Clinical Investigations)
Cleveland Clinic (ogbujic@ccf.org)
Ph.D. Student Case Western Reserve University
(chimezie.thomas-ogbuji@case.edu)


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Received on Friday, 10 April 2009 01:43:39 GMT

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