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[RIF][RAF] Production rules and Horn rules

From: Boley, Harold <Harold.Boley@nrc-cnrc.gc.ca>
Date: Tue, 7 Mar 2006 06:02:50 -0500
Message-ID: <E4D07AB09F5F044299333C8D0FEB45E92DD64D@nrccenexb1.nrc.ca>
To: <public-rif-wg@w3.org>
> - Roadmap
> ACTION: Frank to make his point about semantics of production rules on
> the mailing list
> ACTION: Harold to explain technically the basis
> for interoperation between PR and Horn rules
Basic interoperation could be permitted on top of scopes (modules) of sets
of facts used 'read-only' by Horn rules and 'read-write' by production rules.
Production rules were formally explored in Active Database Systems,
e.g. by Jennifer Widom and colleagues:
J. Widom and S.J. Finkelstein. Set-Oriented Production Rules in Relational Database Systems <http://infolab.stanford.edu/pub/papers/rule-language.ps> . Proceedings of the ACM SIGMOD International Conference on Management of Data, pages 259-270, Atlantic City, New Jersey, May 1990. 
J. Widom. A Denotational Semantics for the Starburst Production Rule Language <http://infolab.stanford.edu/pub/papers/denotational.ps> . ACM SIGMOD Record, 21(3):4-9, September 1992.

The interoperation of Horn rules and production rules themselves could start
with an expressive intersection of these two classes of rules. This may consist
of an appropriate subset of -- syntactically sugared -- Horn rules (e.g., slotted
Datalog) that also is a -- small -- subset of production rules (e.g., just having
'look-up' conditions and 'assert' actions). It is called 'pure production rules' in
the Preliminary Design Roadmap, and moved to Phase 1, #4 for early studies:
(In the Charter, production rules were only in Phase 2, 3.2.5. Actions.)
A benefit is that any extension we consider for the Phase 1 Horn conditions
(e.g., NAF queries or built-in calls) could already be assessed for its merits
in conditions of  'full production rules' in Phase 2. A cross-fertilization may
take place between (Web) extensions of the two kinds of rules.
Frank's concern that the intersection is too small etc. should be carefully
considered, first, by working on a taxonomy of desirable RIF actions.
-- Harold

Received on Tuesday, 7 March 2006 11:02:57 UTC

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