YES(?,O(n^1))

Problem:
 rev(nil()) -> nil()
 rev(rev(x)) -> x
 rev(++(x,y)) -> ++(rev(y),rev(x))
 ++(nil(),y) -> y
 ++(x,nil()) -> x
 ++(.(x,y),z) -> .(x,++(y,z))
 ++(x,++(y,z)) -> ++(++(x,y),z)
 make(x) -> .(x,nil())

Proof:
 Bounds Processor:
  bound: 1
  enrichment: match
  automaton:
   final states: {5,4,3}
   transitions:
    .1(1,6) -> 6,4
    .1(2,3) -> 5*
    .1(2,9) -> 6,4
    .1(1,3) -> 5*
    .1(1,9) -> 6,4
    .1(2,6) -> 6,4
    nil1() -> 3*
    ++1(1,2) -> 9*
    ++1(2,1) -> 6*
    ++1(1,1) -> 6*
    ++1(2,2) -> 6*
    rev0(2) -> 3*
    rev0(1) -> 3*
    nil0() -> 1*
    ++0(1,2) -> 4*
    ++0(2,1) -> 4*
    ++0(1,1) -> 4*
    ++0(2,2) -> 4*
    .0(1,2) -> 2*
    .0(2,1) -> 2*
    .0(1,1) -> 2*
    .0(2,2) -> 2*
    make0(2) -> 5*
    make0(1) -> 5*
    1 -> 6,4
    2 -> 6,9,4
  problem:
   
  Qed