YES
O(n^4)
TRS:
 {
            i(0()) -> 0(),
           i(i(x)) -> x,
        i(+(x, y)) -> +(i(x), i(y)),
         +(x, 0()) -> x,
        +(x, i(x)) -> 0(),
     +(x, +(y, z)) -> +(+(x, y), z),
         +(0(), y) -> y,
        +(i(x), x) -> 0(),
  +(+(x, y), i(y)) -> x,
  +(+(x, i(y)), y) -> x
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
              i(0()) -> 0(),
             i(i(x)) -> x,
          i(+(x, y)) -> +(i(x), i(y)),
           +(x, 0()) -> x,
          +(x, i(x)) -> 0(),
       +(x, +(y, z)) -> +(+(x, y), z),
           +(0(), y) -> y,
          +(i(x), x) -> 0(),
    +(+(x, y), i(y)) -> x,
    +(+(x, i(y)), y) -> x
   }
  Matrix Interpretation:
   Interpretation class: triangular
       [X7]  [X3]    [1 0 0 0][X7]   [1 0 0 1][X3]   [1]
       [X6]  [X2]    [0 1 0 0][X6]   [0 1 0 0][X2]   [0]
   [+]([X5], [X1]) = [0 0 1 0][X5] + [0 0 1 0][X1] + [1]
       [X4]  [X0]    [0 0 0 1][X4]   [0 0 0 1][X0]   [1]
   
       [X3]    [1 1 0 1][X3]   [0]
       [X2]    [0 1 1 0][X2]   [1]
   [i]([X1]) = [0 0 1 0][X1] + [0]
       [X0]    [0 0 0 1][X0]   [0]
   
         [0]
         [0]
   [0] = [0]
         [1]
   
   
   Qed