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Re: SeRQL an RDF rule language: scopingRulesvsQueryinW3Cwork

From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
Date: Tue, 4 Nov 2003 09:28:29 +0000
To: www-rdf-rules@w3.org
Message-ID: <20031104092829.GC30678@ecs.soton.ac.uk>

On Mon, Nov 03, 2003 at 06:56:28 -0500, Geoff Chappell wrote:
> > In this light, do folks on these lists think it is sustainable to
> > maintain that there's an interesting distinction still to be made
> > between work on RDF 'query' languages vs 'rules' languages.
> 
> It's probably hard to get away from the fact that the body of a rule
> will likely look like a query, but I can imagine there could be some
> differences at the edges. For example, w/RDF Gateway[1] I often find
> myself using decidedly closed-world type things in queries (aggregation
> functions, negation-as-failure) that I wouldn't usually use in a rule

You may well in rules too, eg. to add something along the lines of
default reasoning. Anything with a closed world flavour would surely be
contraversial in RDF query too though.

> I can also imagine a scenario in which sw rules come out of the gate
> more constrained (e.g. owl-rules [2]) than you'd want in a query
> language (e.g. I'd want to be able to have a variable in the predicate
> position of triple in a query language). If that occurred it would be
> good to separate them.

You may well need predicate variables in rules to, eg. to construct the
reified triple from its source triple (not that I'd suggest you should do
that ;). I agree about ordering and so on though, but they are a small
part of the RDF query mechanism.

> > Can folks here imagine a workable W3C RDF Query WG constrained not to
> > get into Rules WG territory, but to maximise compatibility with a
> > (future? parallel) Working Group on Rule languages for RDF? Or are the
> > two technology areas too close?
> 
> I'd hate to see two different solutions to the same (or very similar)
> problem. Maybe that's not the inevitable outcome of two groups,
> though....

I think that there would have to be a very good reason for the syntax of
the "from" part to be substantially different.

- Steve
Received on Tuesday, 4 November 2003 04:28:31 UTC

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