YES(?,O(n^1))

Problem:
 s(b(x1)) -> b(s(s(s(x1))))
 s(b(s(x1))) -> b(t(x1))
 t(b(x1)) -> b(s(x1))
 t(b(s(x1))) -> u(t(b(x1)))
 b(u(x1)) -> b(s(x1))
 t(s(x1)) -> t(t(x1))
 t(u(x1)) -> u(t(x1))
 s(u(x1)) -> s(s(x1))

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {4,3,2}
   transitions:
    s1(19) -> 20*
    s1(8) -> 9*
    u1(12) -> 13*
    t1(11) -> 12*
    b1(9) -> 10*
    s0(1) -> 2*
    b0(1) -> 4*
    t0(1) -> 3*
    u0(1) -> 1*
    1 -> 11,8
    9 -> 19*
    10 -> 4*
    13 -> 12,3
    20 -> 9,19,2
  problem:
   
  Qed