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Re: Signalling entailment in queries

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Wed, 21 Jul 2010 08:50:16 -0400
To: "Lee Feigenbaum" <lee@thefigtrees.net>
cc: "Sandro Hawke" <sandro@w3.org>, "SPARQL Working Group" <public-rdf-dawg@w3.org>
Message-ID: <C86C6548.12851%ogbujic@ccf.org>
On 7/20/10 10:53 PM, "Lee Feigenbaum" <lee@thefigtrees.net> wrote:
> On 7/20/2010 9:16 PM, Chimezie Ogbuji wrote:
> I may weigh in on the rest of this discussion at some other point, but I
> don't really think the comparison with LET is particularly salient. For
> one thing, LET was one of the top 1 or 2 considered features that missed
> the cut, while parametrized inference was not; but that aside, LET has
> several implementations, including new implementations since the WG
> defined the original scope of our work. It also benefits from
> potentially having semantics that are already defined within the query
> language document. As far as I can tell, none of this is true for
> parametrized inference.

I can understand the argument around priority (there being more of a need
for one feature over another), but with regards to implementations, I should
point out that standards don't always follow extant implementations (and in
fact they rarely do as far as I can tell).

As for the ability to indicate which entailment regime to use, there is no
'semantics' necessary.  The semantics of the answers you get from using
various entailment regime is currently defined and they are well-identified.
This is simply a matter of indicating which one you want to use in the
query.  So, I'm not sure what you mean when you suggest that this ability
lacks a well-defined semantics.

> As a WG Chair, I have been hesitant to expand
> our scope at all with LET, which is one reason I've let it drag on for
> so long; similarly, I'm extremely wary of taking on a new task such as
> signalling entailment, particularly given that this thread has
> illuminated many wide-open design decisions that would seem to need to
> be made without the ability to lean on existing implementations.

Frankly, I don't see any 'wide-open' design decisions other than perhaps the
question of granularity (i.e., can you specify an entailment regime at the
level of a graph graph pattern).

-- Chime


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Received on Wednesday, 21 July 2010 13:05:01 GMT

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