YES
O(n^4)
TRS:
 {app(app(apply(), f), x) -> app(f, x)}
 DUP: We consider a non-duplicating system.
  Trs:
   {app(app(apply(), f), x) -> app(f, x)}
  Matrix Interpretation:
   Interpretation class: triangular
             [0]
             [0]
   [apply] = [0]
             [1]
   
         [X7]  [X3]    [1 1 0 0][X7]   [1 1 0 0][X3]   [0]
         [X6]  [X2]    [0 0 0 1][X6]   [0 1 0 0][X2]   [0]
   [app]([X5], [X1]) = [0 0 0 0][X5] + [0 0 0 0][X1] + [0]
         [X4]  [X0]    [0 0 0 1][X4]   [0 0 0 1][X0]   [1]
   
   
   Qed