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