Problem:
 a() -> b()
 f(x,a()) -> f(b(),b())
 f(b(),x) -> f(b(),b())
 f(f(x,y),z) -> f(b(),b())

Proof:
 Nonconfluence Processor:
  terms: f(f3(),b()) *<- f(f3(),a()) ->* f(b(),b())
  Qed
  
  first automaton:
   final states: {9}
   transitions:
    b() -> 10*
    f(11,10) -> 9*
    f3() -> 11*
  
  second automaton:
   final states: {6}
   transitions:
    b() -> 8,7
    f(8,7) -> 6*