YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 0
  enrichment: match
  automaton:
   final states: {4,3,2}
   transitions:
    a0(1) -> 2*
    b0(1) -> 3*
    c0(1) -> 4*
    f60() -> 1*
    1 -> 4,3,2
  problem:
   
  Qed