How is the not conditional expression implemented? I am using it as a gate expression - I can't remember if that's the correct technical term or not, basically I'm using that expression to prevent the rules engine from having to evaluate additional expressions on the same rule which I know to be somewhat expensive and potentially frequently evaluated and added to the agenda, but only infrequently executed (due to highly dynamic facts). In the testing I have done, it seems to work well, but I'm not sure if there's a certain number of facts where the not CE calculation will outweigh the thing it's preventing. Is the not CE something that's optimized, or does the rules engine have to look through all the facts of that type to determine if the not CE is true? In my case there could be 10's of thousands of the fact on which I have the not CE. -- View this message in context: http://drools.46999.n3.nabble.com/Implementation-of-not-conditional-expre... Sent from the Drools: User forum mailing list archive at Nabble.com.