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