[jboss-jira] [JBoss JIRA] Closed: (JBRULES-1559) Ability to negate a constraint group

Ability to negate a constraint group ------------------------------------ Key: JBRULES-1559 URL: https://issues.jboss.org/browse/JBRULES-1559 Project: Drools Issue Type: Feature Request Security Level: Public(Everyone can see) Components: drools-compiler Affects Versions: FUTURE Reporter: Dirk Bergstrom Assignee: Edson Tirelli Priority: Minor I want to write a rule that says "Find all long-eared dogs that do not have short, black hair". This seems like the simple way to do it: collect( Dog( ears=="long", not (hair=="short" && color=="black") ) But that doesn't parse. Some digging through the archives unearthed a mention of De Morgan's laws, which leads to: http://en.wikipedia.org/wiki/De_Morgan's_laws Which explains that I can instead write: collect( Dog( ears=="long", (hair!="short" || color!="black") ) Which, after some mental effort, turns out to be the right thing. However, had I not found the reference to De Morgan's Law, it would have taken me a long time to get there (if indeed I ever would have). The end result is also quite difficult to parse if you're not a logician, and thus not very user-friendly.