YES
O(n^5)
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
       [X9]  [X4]    [1 3 0 2 2][X9]   [1 3 0 2 0][X4]   [3]
       [X8]  [X3]    [0 1 0 0 0][X8]   [0 1 0 0 0][X3]   [2]
   [f]([X7], [X2]) = [0 0 1 0 0][X7] + [0 0 1 0 0][X2] + [0]
       [X6]  [X1]    [0 0 0 1 1][X6]   [0 0 0 1 2][X1]   [2]
       [X5]  [X0]    [0 0 0 0 1][X5]   [0 0 0 0 1][X0]   [0]
   
       [X9]  [X4]    [1 1 0 2 0][X9]   [1 3 0 0 0][X4]   [2]
       [X8]  [X3]    [0 1 0 0 0][X8]   [0 0 0 0 0][X3]   [2]
   [h]([X7], [X2]) = [0 0 1 0 0][X7] + [0 0 0 0 0][X2] + [0]
       [X6]  [X1]    [0 0 0 0 0][X6]   [0 0 0 1 0][X1]   [0]
       [X5]  [X0]    [0 0 0 0 0][X5]   [0 0 0 0 1][X0]   [0]
   
   
   Qed