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

Proof:
 Bounds Processor:
  bound: 3
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    c1(10) -> 11*
    c1(9) -> 10*
    a1(8) -> 9*
    b1(6) -> 7*
    b2(16) -> 17*
    a0(1) -> 2*
    a2(22) -> 23*
    b0(1) -> 3*
    b3(26) -> 27*
    c0(1) -> 1*
    1 -> 6,2
    6 -> 22*
    7 -> 8,2
    8 -> 16,9
    11 -> 23,17,2
    17 -> 9*
    22 -> 26,23,17
    23 -> 17,9
    27 -> 23,17
  problem:
   
  Qed