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RE: PRD (Prod Rule Dialect) breakout scribe notes from F2F8 6 Nov 07

From: Gerd Wagner <wagnerg@tu-cottbus.de>
Date: Wed, 7 Nov 2007 12:24:08 +0100
To: 'Hassan At-Kaci' <hak@ilog.com>
Cc: "'lukichev'" <lukichev@tu-cottbus.de>, <public-rif-wg@w3.org>
Message-ID: <000e01c82130$b79262b0$1ab2a8c0@informatik.tucottbus.de>

Dear Hassan,

> > CSMA: Model theory for the operational semantics may be possible.
> Model Theory and Operational Semantics are orthogonal 
> concepts. Model Theory fits unchanging truth. In this way, 
> stateful computation such as that performed
> by PR systems is at odds with Model Theory. 

for PR systems we need an intertwining of model theory
and a transition system formalism, since the state of
a PR system can be described as a "set of facts" (this
is the view/terminology of business rules approach),
or more formally as a set of (finite?) models, which
is transformed whenever a rule is fired.

> For an example of such a formal
> operational semantics, see a presentation I did this past 
> summer for IFIP
> group on Rewriting (http://rewriting.loria.fr/IFIP-WG1.6/. 
> Slides of my
> talk: http://koala.ilog.fr/wiki/bin/view/Main/HassanAitKaci#17.)

Interesting slides. However, notice that you've simplifed
a few things:

- Business rules are not production rules; business rules are
  expressed by "business people" in plain English (and we have
  to struggle formalizing them in some declarative logic, e.g.
  in the restricted modal logic of SBVR); only after formalizing
  a business rule you may try to implement it in the form of a
  PR (but don't be surprised if this is not always the best
  solution). In our case study
  we show how plain English business rules can be (visually and XML)
  formalized and then mapped to a concrete PR language (Jena and

- I cannot see how your definition of "Agenda" and the "pick"
  operation captures what is really going on in PR engines
  such as ILOG Jrules and JBoss/Drools. 

In fact, the challenge seems to be to define a PR engine feature 
set that allows to define/explain the different execution semantics 
of the major PR engines.

Gerd Wagner 
Email: G.Wagner@tu-cottbus.de

Received on Wednesday, 7 November 2007 11:24:29 UTC

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