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Re: On production rules and phase I&II

From: <jos.deroo@agfa.com>
Date: Wed, 8 Mar 2006 14:35:40 +0100
To: bry@ifi.lmu.de
Cc: public-rif-wg@w3.org
Message-ID: <OF290693CA.2C2B9DA2-ONC125712B.00479567-C125712B.004AA9AB@agfa.com>

I am not used to reactive rules (still reading Paula's thesis)
so don't shoot :-)
What I am used to is

GIVEN
o a collection of facts as a snapshot of the state of the world
o a set of entailment rules (horn but with skolem functions) 

DERIVE
a description of actions such as instatiation, modificatiation, ..

ACT according to the latter derivations (which is completely
separated from the reasoning but can give rise to new state
of the world)

With such assumptions, is the RIF also about the ACT or the
closing of above control loop?

-- 
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/




Francois Bry <bry@ifi.lmu.de>
Sent by: public-rif-wg-request@w3.org
08/03/2006 11:48
 
        To:     public-rif-wg@w3.org
        cc:     (bcc: Jos De Roo/AMDUS/AGFA)
        Subject:        Re: On production rules and phase I&II



Dear All,

I feel very, very uneasy at attempts to specify a declarative semantics
for reactive (or production) rules in terms of declarative (e.g. Horn)
rule counterparts. Indeed, this is possible -- but under very strong
assumptions, like no negation, that are unrealistic in practice.
Furthermore, I believe this is useless for applications.

Reactive rules (including production rules) are inherently imperative
because they specify state transitions. Admitteldy, while in standard
imperative languages states refer to variables, in reactive rule
languages states refer to a "database". But this distinction does not
make reactive rule language more declarative or less imperative.

I suggest to keep bothy fragments of RIF for what they are:
- a declarative fragment with a declarative semantics
- an imperative fragment (that of reactive rules) with an imperative
semantics.

This is what application need. A declarative semantics for reactive (or
production) rules might be a good subject for academic research. Or
might well not be -- my own guess.

Regards,

François
Received on Wednesday, 8 March 2006 13:36:04 GMT

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