NO Problem: not(true()) -> false() not(false()) -> true() or(true(),y) -> true() or(x,true()) -> true() or(false(),false()) -> false() and(true(),true()) -> true() and(x,true()) -> x and(true(),y) -> y and(false(),false()) -> false() not(and(x,y)) -> or(not(x),not(y)) not(or(x,y)) -> and(not(x),not(y)) Proof: Nonconfluence Processor: terms: false() *<- not(or(true(),y)) ->* and(false(),not(y)) Qed