YES
O(n^4)
TRS:
 {
               zeros() -> cons(0(), n__zeros()),
               zeros() -> n__zeros(),
           activate(X) -> X,
  activate(n__zeros()) -> zeros(),
     tail(cons(X, XS)) -> activate(XS)
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
                 zeros() -> cons(0(), n__zeros()),
                 zeros() -> n__zeros(),
             activate(X) -> X,
    activate(n__zeros()) -> zeros(),
       tail(cons(X, XS)) -> activate(XS)
   }
  Matrix Interpretation:
   Interpretation class: triangular
          [X3]    [1 0 1 1][X3]   [1]
          [X2]    [0 1 0 0][X2]   [0]
   [tail]([X1]) = [0 0 1 0][X1] + [0]
          [X0]    [0 0 0 1][X0]   [1]
   
              [X3]    [1 0 1 1][X3]   [1]
              [X2]    [0 1 0 0][X2]   [0]
   [activate]([X1]) = [0 0 1 0][X1] + [0]
              [X0]    [0 0 0 1][X0]   [1]
   
             [1]
             [0]
   [zeros] = [1]
             [1]
   
                [0]
                [0]
   [n__zeros] = [1]
                [0]
   
         [0]
         [0]
   [0] = [0]
         [0]
   
          [X7]  [X3]    [1 0 0 0][X7]   [1 0 0 0][X3]   [0]
          [X6]  [X2]    [0 0 0 0][X6]   [0 1 0 0][X2]   [0]
   [cons]([X5], [X1]) = [0 0 0 0][X5] + [0 0 1 0][X1] + [0]
          [X4]  [X0]    [0 0 0 0][X4]   [0 0 0 1][X0]   [1]
   
   
   Qed