YES

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

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {1}
   transitions:
    a1(9) -> 10*
    a1(13) -> 14*
    a1(15) -> 16*
    f20() -> 2*
    a0(6) -> 7*
    a0(2) -> 3*
    a0(8) -> 1*
    b0(3) -> 4*
    b0(4) -> 5*
    b0(7) -> 8*
    b0(5) -> 6*
    b1(12) -> 13*
    b1(10) -> 11*
    b1(14) -> 15*
    b1(11) -> 12*
    7 -> 9*
    16 -> 8*
    1 -> 4*
  problem:
   
  Qed