Problem: f(x,x) -> g() a() -> b() a() -> c() b() -> b() c() -> c() f(a(),x) -> g() f(b(),x) -> g() f(c(),x) -> g() f(x,a()) -> g() f(x,b()) -> g() f(x,c()) -> g() Proof: Nonconfluence Processor: terms: c() *<- a() ->* b() Qed first automaton: final states: {14} transitions: c() -> 14* second automaton: final states: {15} transitions: b() -> 15*