Hi, I have two doubts : 1) Can't we use mathematical operations like average, sum, max, min, etc on the LHS of rule? If, how can I use it? Please show me an example. 2) Can't we manipulate - add and lookup - on a List object on LHS and RHS? If possible, how can I do it? Please describe using a sample. Thanks in advance Jojan -- View this message in context: http://www.nabble.com/Two-Doubts-tf3838282.html#a10867640 Sent from the drools - user mailing list archive at Nabble.com.