[rules-dev] Firing rules only if action causes updates to data?

Hi Dev team, Its been fascinating to watch the growth of this tool. Here is my question: Rule x: if a = 5 b = 3 then c = 0 Now, I have written this rule to run when a = 5 and b =3. But actually, I would like it to ideally run when a = 5 and b = 3 and c != 0 Now, does the second scenario lead to any savings. In Ilog, the second scenario will result in the rule NOT being added to the agenda whereas it would in the first. I cannot code the second scenario into the rule as the rule ( as seen in UI) needs to match the requirements version ( in Doors) and they do not want to add these to the requirements. I would just like to make the second version for performance. We have noticed that less number of rules would fire. Now, if a = 5, b = 3 and c = 0, is there a way Drools can look at it and say, let me not fire this rule since there is no practical use anyways. If not, what are the ways to automate not firing rules in scenarios where action does NOT cause updates to data. Thanks!!