isFrontEndInvariant :: Rule -> Bool
isFrontEndInvariant r = not (isSignal r) && not (ruleIsInvariantUniOrInj r)
isFrontEndInvariant :: Rule -> Bool
isFrontEndInvariant r = not (isSignal r) && not (ruleIsInvariantUniOrInj r)
isFrontEndInvariant r = not (isSignal r) && not (ruleIsInvariantUniOrInj r)