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Re: Final text for Basic Graph Patterns

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Fri, 20 Jan 2006 01:17:43 -0500
Message-Id: <146bdb5e2f13ea85ed996a60f3bdb01d@isr.umd.edu>
Cc: Dan Connolly <connolly@w3.org>, Pat Hayes <phayes@ihmc.us>, RDF Data Access Working Group <public-rdf-dawg@w3.org>
To: Enrico Franconi <franconi@inf.unibz.it>

On Jan 19, 2006, at 1:00 PM, Enrico Franconi wrote:

> On 19 Jan 2006, at 18:33, Pat Hayes wrote:
>> Of course. You miss my point. I was simply following the general 
>> pattern of how SPARQL queries are defined, using our most recent 
>> attempt at an 'entailment-based' general form of definition, and 
>> applying that to OWL-DL as described in the OWL spec, and seeing what 
>> we finish up with. ( {:a rdf:type :b} is legal OWL-DL, under 
>> appropriate constraints, and is an instance of the query under 
>> binding of a variable to a legal OWL-DL identifier, so... ) I meant 
>> only that if one takes a 'natural' extension of SPARQL to OWL, 
>> keeping the basic form of the definitions but replacing simple 
>> entailment by OWL-DL entailment, then examples like this turn up.
> What I am also saying that you have to transport the syntactic 
> constraints that OWL-DL expressions have, to similar syntactic 
> constraints to SPARQL queries when using OWL-DL entailment. Namely, in 
> queries bnodes and variables are not in property position of any 
> triple, nor in object position of rdf:type triples, and there is no 
> rdf, rdfs, owl vocabulary symbol in the query with the exception of 
> rdf:type in property position.

For the record, I always presumed that for OWL  DL Entailment, you'd 
work with the abstract syntax, as that's how entailment is defined:

So, if I were going to write the spec for SPARQL parameterized  with 
OWL DL entailment, I would first define the abstract syntax of the 
basic query in terms of the abstract syntax (which would only allow 
query variables in certain places), then a transformation to triples of 
that abstract syntax.

So I don't think it's that big of a stretch, actually. You *could* 
define a query syntax with variables in funky places, but it's not 
immediate. And it's not immediate from the SPARQL (it's not *far*, 
cause you can sorta see where some variables "would go" if you tried to 
apply the reverse transformation to triples to sparql GPs).

Received on Friday, 20 January 2006 06:17:52 UTC

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