YES
O(n^4)
TRS:
 {h(x, x) -> x,
  f(x, y) -> h(x, y),
  f(x, y) -> h(y, x)}
 DUP: We consider a non-duplicating system.
  Trs:
   {h(x, x) -> x,
    f(x, y) -> h(x, y),
    f(x, y) -> h(y, x)}
  Matrix Interpretation:
   Interpretation class: triangular
       [X7]  [X3]    [1 0 2 3][X7]   [1 1 2 3][X3]   [3]
       [X6]  [X2]    [0 1 0 0][X6]   [0 1 0 0][X2]   [0]
   [f]([X5], [X1]) = [0 0 1 0][X5] + [0 0 1 2][X1] + [2]
       [X4]  [X0]    [0 0 0 1][X4]   [0 0 0 1][X0]   [2]
   
       [X7]  [X3]    [1 0 0 3][X7]   [1 0 0 1][X3]   [2]
       [X6]  [X2]    [0 0 0 0][X6]   [0 1 0 0][X2]   [0]
   [h]([X5], [X1]) = [0 0 1 0][X5] + [0 0 1 0][X1] + [2]
       [X4]  [X0]    [0 0 0 0][X4]   [0 0 0 1][X0]   [2]
   
   
   Qed