[rules-users] Rule architecture question - avoiding condition duplications

Hi all, I have a general question regarding best practice or perhaps better put as right architecture design. We are using Drools (Expert in particularly) to model and execute the behavior aspects of our service, which revolves around meeting scheduling between various users. My main challenge is how to properly structure the rules so that they provide the desired flexibility to both modify and control over time. Following is a small example which illustrates my question: I need to determine a specific execution time and it is based on many conditions and in general about 15 scenarios where I create a rule per scenario. I find that there is a wide set of conditions that are common to all scenarios. So for example a rule would look like: when a1 == X1 a2 == X2 a3 == X3 a4 == X4 b1 == Y1 Then Something . Another rule would be when a1 == X1 a2 == X2 a3 == X3 a4 == X4 b2 == Y2 Then Something else . As you can see I am duplicating the a' conditions which are the common conditions and the b' is a new unique condition. It seems to me like a poorer code maintainability and possibly performance reduction (but I may be wrong, perhaps this is how rules should be written). I assume this is a common case in rules so my question is what would be the best way (architecturally wise) to implement such cases (e.g. insert a new class that indicates that conditions a' are set and base the rules on the existence of such a class) Thanks Hezi