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RE: Reqirement 3.5: subgraph results

From: Howard Katz <howardk@fatdog.com>
Date: Thu, 6 May 2004 10:44:00 -0700
To: "Steve Harris" <S.W.Harris@ecs.soton.ac.uk>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>

> -----Original Message-----
> From: public-rdf-dawg-request@w3.org
> [mailto:public-rdf-dawg-request@w3.org]On Behalf Of Steve Harris
> Sent: Wednesday, May 05, 2004 8:00 AM
> To: RDF Data Access Working Group
> Subject: Re: Reqirement 3.5: subgraph results

    [ snip ... ]

> This is similar to my concern:
> If a query includes some extension function (after 3.3), say a function
> that takes a radius and the URIs for two geo-spatial co-ordinate nodes and
> returns TRUE if one is in the radius of the other. The complete graph used
> to answer that query is not neccesarily known to the query engine -
> especailly if the function is implemented at a lower level. Asking
> extension functions (for example) to give the triples that it used to
> answer the question seems unneccesarily onerous.

That's really my main question to the group: are we designing a language in
which specific and explicit knowledge of graph structure has to be embedded
in the query? It seems to me that we are or should be, but it's not clear to
me that's been decided one way or another by the group. Has this question
been answered to other people's satisfaction, or are we still in a bit of
murky territory here?

I don't see a contradiction in allowing external functions to do things
under the hood and out of sight btw: they provide a needed escape mechanism
for letting clever implementers get around the limits of having to be
triple-wise explicit in the query. In me 'umble at any rate ...

Received on Thursday, 6 May 2004 14:04:03 UTC

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