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Re: Name of a graph? and FROM and FROM NAMED

From: Kendall Clark <kendall@monkeyfist.com>
Date: Thu, 2 Jun 2005 11:09:51 -0400
To: "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: Yoshio FUKUSHIGE <fuku@w3.org>, public-rdf-dawg@w3.org
Message-ID: <20050602150951.GG30693@monkeyfist.com>

On Thu, Jun 02, 2005 at 12:26:29PM +0100, Seaborne, Andy wrote:

> I propose that if a query contains a dataset description with FROM and FROM
> NAMED then these describe the dataset fully (the service wil not sneak in extra,
> unasked for, graphs)
> 
> Rational: if the application is describing the dataset, then it wants to know
> that the query will execute

That's the rationale? That an application describes a dataset, it "wants to
know that the query will execute"? I don't understand this at all. Did the
sentence get cut off or is that it?

I don't like this proposal, for the reasons I've already stated. I don't
think we should require publishers to be pure query answering services, and
the "the service can refuse to execute the query" thing doesn't help much at
all. An organization doesn't deploy a service in order to refuse to execute
queries per se; a publishing organization may deploy a service to execute
queries with some particular background knowledge.

This issue of whether a service may take some other graph into account when
it answers a query is similar to the question of inference. We've maintained
a principled silence about inference. Why can't we maintain it about
publishing services adding to the background graph?

In other words, part of the objection, I *think*, is that you can't be sure
of the results if a service is adding triples to the background graph. That
it's hard to write tests. Well, you can't be sure of them if the service is
doing one of a vast number of different sorts of inference.

In fact, these issues, are from one perspective, *precisely* the same: if my
query service does inference (either to named or to background graphs or to
all the graphs in the dataset), that may well mean that triples will be
added to one or to all of these graphs. If we're silent about adding triples
via inference, I don't see the point of not being silent about adding told
triples too.

I don't see how we can abjure the addition of told triples without also
abjuring the addition of inferred triples.

Kendall Clark
Received on Thursday, 2 June 2005 15:10:23 GMT

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