YES(?,O(n^1))

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

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {4,3,2}
   transitions:
    b1(17) -> 18*
    a1(5) -> 6*
    a1(16) -> 17*
    r1(15) -> 16*
    l1(6) -> 7*
    a0(1) -> 2*
    l0(1) -> 1*
    r0(1) -> 3*
    b0(1) -> 4*
    1 -> 15,5
    7 -> 6,2
    18 -> 4*
  problem:
   
  Qed