YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {3}
   transitions:
    f1(11,8) -> 3*
    f1(13,8) -> 11*
    f1(8,8) -> 9*
    f1(8,10) -> 11*
    f1(8,12) -> 13*
    f1(9,3) -> 10*
    f1(9,9) -> 12*
    f1(9,11) -> 10*
    a1() -> 8*
    f0(3,3) -> 3*
    a0() -> 3*
  problem:
   
  Qed