[rules-users] Rule partitioning in a stateful control system

[Steve]

Hi, I was wondering what people this might think is good solution to the 
following scenario...

I have a Fact that represents a physical piece of equipment in a control 
system, this Fact has a number of parameters, param1 and param2. The working 
memory is used in a stateful manner. Consider two example rules, cs is a 
global vairable that allows calls back to the control system.

rule "Monitor param1"
  when
   f : Fact( param1 == 1 )
  then
   cs.DoSomething(f);
end

rule "Monitor param2"
  when
   f : Fact( param2 == 1)
  then
    cs.DoSomething(f);
end

If param1 is updated to == 1, the working memory notified (modifyObject) and 
the the rules are fired (fireAllRules), consequently the rule "Monitor param1" 
will be placed onto the Agenda. Assuming that sometime later param2 is updated 
to == 1, notifing the working memory and firing the rules again will result in 
rules "Monitor param1" and "Monitor param2" being placed on the agenda. What I 
really want is just the change to be detected and not for the "Monitor param1" 
rule to fire again.
Is there a pattern to acheive the desired behaviour, I have used agenda-group 
but am not sure this is the best solution.

Thanks for your help.