Thanks - and thanks for the tutorial for our members. And, yes, I
have taught the difference between the two and, since I usually use
goal-oriented programming, I prefer MEA. However, I see your point
where you might be more comfortable with LEX. BTW and FYI, the
original OPS used on XCON was a LEX system. Only later did Newell
and Forgy institute MEA and goal-oriented approach. I guess I'm just
in a rut with goal-oriented and hate to move out. :-)
SDG
jco
James C. Owen
Senior Consultant
[EMAIL PROTECTED]
http://www.kbsc.com
"Never give up. Never give up. Never, never, never give up."
From a speech by former Prime Minister, Winston Churchill, during
the most trying times of the British Empire; a great leader too soon
forgotten by his country after keeping it from being swallowed up by
the Nazi Empire during the second world war.
On Mar 13, 2006, at 5:39 PM, Steve Solomon wrote:
I'm sure you know how LEX and MEA work, so the following
explication is
for the benefit of the wider mailing list audience:
In the LEX conflict resolution strategy, rule activations are
ordered by
recency (as in the current Jess "depth" strategy). Among activations
with the same recency, activations are ordered according to the
specificity of their condition elements. The most recent rule
activation
with the most specific left-hand side (LHS) is fired first.
Specificity
refers to the total number of tests within all of the conditions of a
rule.
The MEA strategy (Means-Ends Analysis) has the same recency and
specificity conditions as LEX, but places extra emphasis on the
recency
of a working memory element that matches the first condition
element of
a rule's LHS.
MEA is used to facilitate the orderly handling of subgoals. If the
first
condition element of a rule is always a goal element, then the system
will never be distracted by a very recent working memory element
that is
not a goal. (Brownston, Farrell, Kant, and Martin, Programming Expert
Systems in OPS5, 1985(!?))
So presumably, the LEX strategy is intended to be used in systems
where
the orderly handling of subgoals is not needed or would get in the way
of a more "organic" rule organization -- all condition elements in
a set
of rules having the same "weight" relative to each other.
I could think of a number of domains where one could prefer the looser
LEX strategy over MEA, for example an (object) classification
system and
a plan recognition system. In both cases, one possible approach is to
let the entire LHS of some set of rules represent the pattern being
recognized, without adornment of a goal element. Of course, the same
domains could be implemented using MEA too. It all boils down to
programming style and preferences.
-Steve Solomon
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of James C. Owen
Sent: Monday, March 13, 2006 2:27 PM
To: [email protected]
Subject: Re: JESS: Announcing Jess 7.0b6
OK, now I just "have" to know; why would anyone prefer LEX to MEA
(Means Ends Analysis) for conflict resolution? I thought that Dr.
Newell et al had reported on this quite some time ago and they showed
why MEA was preferable to LEX. Like, the early 80's? So, again,
why? (Not being argumentative - just looking for information...)
SDG
jco
On Mar 13, 2006, at 12:20 PM, Steve Solomon wrote:
Is there any update on when the LEX conflict resolution strategy
might
be implemented?
Thanks,
Steve Solomon
USC Institute for Creative Technologies
[EMAIL PROTECTED]
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:owner-jess-
[EMAIL PROTECTED]
On Behalf Of [EMAIL PROTECTED]
Sent: Sunday, March 12, 2006 6:39 PM
To: Jess Mailing List
Subject: JESS: Announcing Jess 7.0b6
Hi Folks,
Version 7.0b6 of Jess, the Java Programmer's Rule Engine, is
available
for download at the usual place:
http://www.jessrules.com/download.shtml
This version includes substantial documentation updates and some very
nice usability enhancements, including "Java Patterns" -- a new
syntax
for writing simple slot tests that is more readable and natural for
Java programmers to use. From the change log:
Fix bug in (logical) when modifying working memory from
nested scopes (thanks Yuri Gribov). Added "add"
function. Added "Java patterns." Deprecated
executeCommand() in favor of eval(). Massive
manual rewrites. Another logical/slot-specific bug
fixed (thanks Shan Ming Woo.) Rete member in
ClassSource transient (thanks Jonathan Sewall.)
Overloaded updateObject() accepting property name (for
Lakshmi Vempati). Fix synchronization of "undefinstance
*" (thanks Abdul Quddoos Khan). Slight change to "accumulate"
semantics (thanks Shan Ming Woo.) Overloaded "add()"
methods in ValueVector.
The final release of Jess 7 is getting very close. As usual,
comments
and questions are welcome on the mailing list at jess-
[EMAIL PROTECTED]
or directly to me at [EMAIL PROTECTED] Your feedback now is more
important than ever.
---------------------------------------------------------
Ernest Friedman-Hill
Advanced Software Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://herzberg.ca.sandia.gov
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