YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {3,2}
   transitions:
    b1(5) -> 5,3
    f1(1,1) -> 5*
    a0(1) -> 2*
    f0(1,1) -> 3*
    b0(1) -> 1*
  problem:
   
  Qed