YES(?,O(n^2))
TRS:
 {
    +(x, 0()) -> x,
    +(x, s y) -> s +(x, y),
  +(0(), s y) -> s y,
  s +(0(), y) -> s y
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
      +(x, 0()) -> x,
      +(x, s y) -> s +(x, y),
    +(0(), s y) -> s y,
    s +(0(), y) -> s y
   }
  Matrix Interpretation:
   Interpretation class: triangular
       [X1]    [1 0][X1]   [0]
   [s]([X0]) = [0 1][X0] + [2]
   
         [1]
   [0] = [3]
   
       [X3]  [X1]    [1 0][X3]   [1 3][X1]   [0]
   [+]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [3]
   
   
   Qed