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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
  http://oxygen.informatik.tu-cottbus.de/rewerse-i1/?q=node/33#head-3
  we show how plain English business rules can be (visually and XML)
  formalized and then mapped to a concrete PR language (Jena and
  JBoss/Drools).

- 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

-------------------
Gerd Wagner 
http://oxygen.informatik.tu-cottbus.de/IT
Email: G.Wagner@tu-cottbus.de
 

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

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