YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 2
  enrichment: match
  automaton:
   final states: {3}
   transitions:
    a1(10) -> 11*
    a1(8) -> 9*
    b1(12) -> 13*
    b1(9) -> 10*
    a2(20) -> 21*
    a2(22) -> 23*
    a0(3) -> 3*
    b2(21) -> 22*
    b0(3) -> 3*
    3 -> 8*
    10 -> 20*
    11 -> 9,12,3
    13 -> 10*
    23 -> 9*
  problem:
   
  Qed