YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 0
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    a0(1) -> 2*
    s0(1) -> 1*
    b0(1) -> 3*
  problem:
   
  Qed