OK. It took me a few laps with the debugger to understand what is happening with the following: rule when $assignment: Assignment($resource: resource) not Booking(resource == $resource) then insertLogical(new Booking($resource)); end Basically, in the rhs the insertion of the new Booking causes the lhs to be reevaluated, and since in the reevaluation, there IS a Booking, it is retracted. Then the lhs is reevaluated to see that there is NOT a Booking, and so the rhs is run again, and loop and loop and loop. But what I don't understand, is if I add an update in the rhs like this: rule when $assignment: Assignment($resource: resource) not Booking(resource == $resource) then update($assignment); insertLogical(new Booking($resource)); end there isn't a loop. I didn't take the journey with the debugger to answer this question, but am still wondering: why does the update break the infinite loop? Thanks, John -- View this message in context: http://www.nabble.com/looping-due-to-immediate-retraction-tf4847517.html#... Sent from the drools - user mailing list archive at Nabble.com.