Problem: c() -> f(c()) c() -> h(c()) f(x) -> f(f(x)) h(x) -> h(h(x)) Proof: Nonconfluence Processor: terms: h(c()) *<- c() ->* f(c()) Qed first automaton: final states: {1} transitions: c() -> 2* f(2) -> 2* h(2) -> 2,1 second automaton: final states: {3} transitions: c() -> 4* f(4) -> 4,3 h(4) -> 4*