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