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

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    b1(5) -> 6*
    c1(4) -> 5*
    a0(1) -> 2*
    b0(1) -> 3*
    c0(1) -> 1*
    1 -> 4*
    6 -> 2*
  problem:
   
  Qed