[rules-users] logical 'not' - is there such a construct?

Hi, I wonder if there is logical 'not' operator (in the meaning of "!=" -> 'not equal') which can be applied to the whole rule? Eg: Rule x When ! ( MyObject(aaa == "bbb") MyObject2(bbb == "aaa") ) Then // do smth End Basically I'm looking for an operator to reverse the evaluation result of the expression in the brackets. The use case: in my system all rules are defined from 'rule passes' prospective, while the application should take some action in case the rule is NOT passed (ie, 'else' case). Any way to do that except reformulating the constraints themselves? Thanks, Vlad