Hello, Please guide me to implement following rule. I would like to found out the city where absence of either Male or Female found for same age. I also need to have ref to those Men and Female of that city in collection to use it RHS. Also there will be max of one male & female for same age. Male{ String name; int age; String city } Female{ String name; int age; String city } Thanks -- View this message in context: http://www.nabble.com/help-in-writing-this-rule-logic-tp22817412p22817412... Sent from the drools - user mailing list archive at Nabble.com.