Problem:
 a(x1) -> x1
 a(a(b(b(x1)))) -> b(b(a(a(b(a(x1))))))

Proof:
 Bounds Processor:
  bound: 0
  enrichment: match
  automaton:
   final states: {2}
   transitions:
    a0(1) -> 2*
    b0(1) -> 1*
    1 -> 2*
  problem:
   
  Qed