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Re: What is an RDF Query?

From: David Allsopp <d.allsopp@signal.qinetiq.com>
Date: Thu, 20 Sep 2001 09:16:26 +0100
Message-ID: <3BA9A5DA.E69ABFC8@signal.qinetiq.com>
CC: www-rdf-rules@w3.org

Pat Hayes wrote:

> >The reason calling the trigger a query made sense to me is that I
> >visualise the situation as follows:
> >I have a rule engine and set of rules. There is a separate knowledge
> >base of assertions somewhere, on disk or on the network. 'I' (the rule
> >engine) know that (P implies Q). But has P been asserted, and can I
> >therefore infer Q? That's in the knowledge base, so I have to *query*
> >the knowledge base in order to tell whether P has been *asserted*.
> OK,I see what you mean. But you have missed out a step. You (the rule
> engine) query the KB: you say
> P?
> to the KB. Presumably, the KB gives you an answer, which is an
> assertion (not  a query):
> P
> (or maybe 'yes', which has the same content when given as an answer
> to your query;)
> and then you take *that answer* and run the rule on it:
> P and (P implies Q)
> to get the assertion
> Q.
> But its the output *from* the KB that triggers the rule, not your
> query *to* it. If the KB had said 'no', the rule wouldn't have been
> triggered, right?

Yes, absolutely.


David Allsopp.

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Received on Thursday, 20 September 2001 04:17:30 UTC

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