[rules-users] Multivariable and multislots

Hi, I was wondering how I can express pattern matchings in drools that operate on sets of values (multivalues). As an example I composed a Jess/Clips rule that is able to match every block that has a green as well as a red block on top of it. (deftemplate Block (slot name(type STRING)) (slot color(type STRING)) (multislot on (type symbol)) ) (defrule multimatch ?b1 <- (Block (on $?a1 ?x $?c1) (color "red")) ?b2 <- (Block (on $?a2 ?x $?c2) (color "green")) =>(printout t "match multimatch:" ?x ?b1 ?b2)) This rules triggers for every value of the multislot "on" which is contained in both multifields. I tried playing around with "memberof" and "contains" in drools but found no possibility to operate on two sets. Is it possible? Kind regards, Lars