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[RIF]: Append solution using pure production rules

From: Vincent, Paul D <PaulVincent@fairisaac.com>
Date: Fri, 17 Mar 2006 00:22:37 -0800
Message-ID: <B3636F07C8359844A9A2370C5EA08CCBD39E29@SRFMSGMB00.corp.fairisaac.com>
To: "Francois Bry" <bry@ifi.lmu.de>, <public-rif-wg@w3.org>

<<Thus, once again we are left with the observation that production rules seems a well-defined computing paradigm, but in fact is not. It is a nebula of languages each with different semantics. Indeed, there are no general agreement on a common semantics for alll production rule languages -- as opposed to declarative languages based on first-order logic formulas and Horn clauses.>>

This is indeed a justification for RIF in the production rule world. I do not have customers clamouring for a mapping between PR & FOL, but a generic cross-vendor PR RIF would be useful to them. [This is not to say there isn't a role for FOL in business IT etc: just that generally, like the semantic web, its not in use today].

Note that we are working on a "common" semantic subset of PR in PRR, based on the (relatively common, but by no means universal) Rete and sequential/procedural semantic models. PRR Core is also designed to be extensible to other (IT) rule types.

Paul Vincent
Fair Isaac Blaze Advisor --- Business Rule Management
OMG PRR and W3C RIF for rule standards
 
-----Original Message-----
From: public-rif-wg-request@w3.org [mailto:public-rif-wg-request@w3.org] On Behalf Of Francois Bry
Sent: Friday, March 17, 2006 8:04 AM
To: public-rif-wg@w3.org
Subject: Re: Append solution using pure production rules


Dear All,

As of whether or not production rules give rise to implement a recursive
computation process, the following should, I think, be considered.

Some brands of production rule languages, as they have been described in
the literature over the last 2 to 3 decades, significantly restrict the
re-firing of a rule that has already fired. In extreme cases, a rule can
only fire once. (Some other brands of production rule languages either
do not know such restriction or know such restrictions, but make it
possible to disallow them.)

If  the firing of a production rule at different cycles of the
computation is possible, then, in principal recursive computation can be
expressed. The proviso "in principle" is only necessary because of 
technicalities (such as primitives for list concatenation) that a given
production rule language might not offer.

It is worth stressing that proponents of production rule language have
in the past claimed that precluding recursion with production rules was
an advantage. (The oppositie viewpoint has often been expressed, too.)

I think, Hassan's remark should be understood in this historical context.

Thus, once again we are left with the observation that production rules
seems a well-defined computing paradigm, but in fact is not. It is a
nebula of languages each with different semantics. Indeed, there are no
general agreement on a common semantics for alll production rule
languages -- as opposed to declarative languages based on first-order
logic formulas and Horn clauses.

Regards,

François
Received on Friday, 17 March 2006 08:23:21 GMT

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