YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 0
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    a0(1) -> 2*
    b0(1) -> 3*
    f40() -> 1*
    1 -> 3,2
  problem:
   
  Qed