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Re: [TF-ENT] OWL Direct Semantics added

From: Ivan Herman <ivan@w3.org>
Date: Tue, 24 Nov 2009 13:28:12 +0100
Message-ID: <4B0BD15C.8060906@w3.org>
To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>
Hi Birte,

I share your unhappiness:-)... and I am wondering. I am not sure we
discussed how a user would choose among the various entailment regimes a
system provides (maybe different URI-s correspond to different
regimes?). Also, I am not sure about a conformance issue: would all
SPARQL implementation have to implement simple entailment as a minimum?

However... let us suppose that (a) each system has simple entailment as
a possibility and (b) the user can choose which entailment is used for a
specific query. Do we then really need this mixed semantics? What are
the use cases? After all, the user can then choose to run simple
entailment for queries on annotations...

I presume you guys discussed that...

A tiny editorial issue, too. You write:

[[[
SPARQL is only defined for basic graph patterns that can be instantiated
into RDF triples. For OWL 2 Direct Semantics, an extension to BGPs in
functional style syntax (FSS) or other popular OWL syntaxes seems
natural, but is not part of this specification.
]]]

though I understand the intention, I am not sure this is editorially
correct. Isn't it correct that anything that I write down in FSS can be
expressed in RDF graphs (even if it is ugly:-)? If so, the issue is not
with BGP-s or an extension thereof, but the triple-based syntax used in
the BGP and a possibly alternative based on, say, FSS. Ie, something like

[[[
SPARQL is only defined for basic graph patterns using a triple-based
syntax. For OWL 2 Direct Semantics, an alternative syntax for BGPs based
on functional style syntax (FSS) or other popular OWL syntaxes seems
natural, but is not part of this specification.
]]]

I may have got something wrong...

Ivan

Birte Glimm wrote:
> Hi all,
> I have added a section about OWL Direct Semantics:
> http://www.w3.org/2009/sparql/docs/entailment/xmlspec.xml
> 
> I am not really happy with the work-around for querying for
> annotations, but it seems users really want to query for them and
> Direct Semantics simply ignores annotations. I am happy about any
> feedback/alternative suggestions for that and for any other parts of
> the section.
> 
> Birte
> 
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
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Received on Tuesday, 24 November 2009 12:28:45 GMT

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