NO Problem: f(g(x)) -> g(f(f(x))) g(x) -> x Proof: Nonconfluence Processor: terms: f(f2()) *<- f(g(f2())) ->* g(f(f(f2()))) Qed first automaton: final states: {1} transitions: f(2) -> 1* f2() -> 2* second automaton: final states: {3} transitions: g(6) -> 3* f(4) -> 5* f(5) -> 6* f2() -> 4* 6 -> 3*