YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 0
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    a0(1) -> 2*
    f0(1,1) -> 3*
    b0() -> 1*
  problem:
   
  Qed