Perhaps this is of interest: The original code had two rules - the only ones with accumulate - as the fifth and sixth rule between (reset) and (run), and the problem didn't surface until I added number 6.
-W

Ernest Friedman-Hill wrote:

This appears to be an "incremental reset" bug. The term "incremental reset" refers to the special processing that has to be done to bring a rule up to date if it's added to an already-populated working memory. Jess expects you to do things the other way around: compile the Rete network by defining all the rules, and then push the data through it; and indeed, if you move your "reset" to after the rules are defined, they both fire correctly.

Thanks for the report; we'll look into this further and get it fixed.

On Jun 27, 2007, at 10:34 AM, Wolfgang Laun wrote:

In the program below, Jess will only fire the second rule if both are uncommented, but each of them fires if the other one isn't there. If the order of rule definitions is reversed, the second one "wins" again.

Jess Version 7.0p1

Kind regards
Wolfgang

(clear)

(deftemplate Obj
   (slot id           (type STRING))
)

(deftemplate Room extends Obj
   (slot occupied (type SYMBOL)(default false)) ; Boolean
)

(deftemplate Suite extends Room
   (slot rooms (type INTEGER)))

(deftemplate Single extends Room)
(deftemplate Double extends Room)


(deftemplate NextTo
   (slot room1 (type STRING))
   (slot room2 (type STRING))
)

(deffacts fact-23
   (Suite  (id "100") (rooms 3))
   (Single (id "101"))
   (Double (id "102"))
   (Double (id "103"))

   (NextTo (room1 "100")(room2 "101"))
   (NextTo (room1 "101")(room2 "100"))
   (NextTo (room1 "101")(room2 "102"))
   (NextTo (room1 "102")(room2 "101"))
   (NextTo (room1 "102")(room2 "103"))
   (NextTo (room1 "103")(room2 "102"))
)

(reset)

;;/***
(defrule oneNext
   "Check that a suite has exactly one neighbour."
   (Suite (id ?rid))
   ?sn <- (accumulate (bind ?xcount 0) (++ ?xcount) ?xcount
                      (NextTo (room1 ?rid)))
   (test (= ?sn 1))
   =>
   (printout t "===> Suite " ?rid " has " ?sn " neighbours." crlf)
)
;;***/

;;/***
(defrule maxNext
   "Check that no room is next to three or more."
   (Room (id ?rid))
   ?nc <- (accumulate (bind ?count 0) (++ ?count) ?count
                      (NextTo (room1 ?rid)))
   (test (<= ?nc 2))
   =>
   (printout t  "---> " ?rid " has " ?nc " neighbours." crlf)
)
;;***/

(run)


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---------------------------------------------------------
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://www.jessrules.com

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