[rules-users] how to sort and validate

Hi, I Have 2 types of objects say AObject1(effdate,terminationdate,status=active) AObject2(effdate,terminationdate,status=inactive) AObject3(effdate,terminationdate,status=active) etc... BObject(effectivedate,id) i want to check such a way that BObject's effective date should be fall within a range of AObjects(list of AObjects) miniumeffectivedate and maximumterminationdate when its status Active. How to write a rule for that Thanks and Regs, Basha