YES
O(n^2)
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
       [X3]  [X1]    [1 0][X3]   [1 0][X1]   [3]
   [f]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [2]
   
       [X3]  [X1]    [1 0][X3]   [1 0][X1]   [2]
   [h]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [2]
   
   
   Qed