YES
O(n^5)
TRS:
 {
  U12(tt(), M, N) -> s(plus(activate(N), activate(M))),
      activate(X) -> X,
  U11(tt(), M, N) -> U12(tt(), activate(M), activate(N)),
    plus(N, s(M)) -> U11(tt(), M, N),
     plus(N, 0()) -> N
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
    U12(tt(), M, N) -> s(plus(activate(N), activate(M))),
        activate(X) -> X,
    U11(tt(), M, N) -> U12(tt(), activate(M), activate(N)),
      plus(N, s(M)) -> U11(tt(), M, N),
       plus(N, 0()) -> N
   }
  Matrix Interpretation:
   Interpretation class: triangular
         [1]
         [0]
   [0] = [0]
         [0]
         [0]
   
          [X9]  [X4]    [1 0 0 0 0][X9]   [1 0 0 2 3][X4]   [0]
          [X8]  [X3]    [0 1 0 0 3][X8]   [0 0 2 0 2][X3]   [0]
   [plus]([X7], [X2]) = [0 0 1 0 3][X7] + [0 0 0 2 3][X2] + [0]
          [X6]  [X1]    [0 0 0 1 2][X6]   [0 0 0 0 1][X1]   [0]
          [X5]  [X0]    [0 0 0 0 1][X5]   [0 0 0 0 1][X0]   [0]
   
       [X4]    [1 0 0 0 0][X4]   [0]
       [X3]    [0 0 0 0 0][X3]   [0]
   [s]([X2]) = [0 0 0 0 1][X2] + [0]
       [X1]    [0 0 0 1 0][X1]   [2]
       [X0]    [0 0 0 0 1][X0]   [3]
   
         [X14]  [X9]  [X4]    [1 0 0 2 2][X14]   [1 0 0 2 3][X9]   [1 0 0 0 0][X4]   [0]
         [X13]  [X8]  [X3]    [0 0 0 0 2][X13]   [0 0 0 0 2][X8]   [0 1 0 0 2][X3]   [0]
   [U11]([X12], [X7], [X2]) = [0 0 0 1 2][X12] + [0 0 0 2 2][X7] + [0 0 0 0 2][X2] + [2]
         [X11]  [X6]  [X1]    [0 0 0 1 0][X11]   [0 0 0 0 1][X6]   [0 0 0 1 2][X1]   [0]
         [X10]  [X5]  [X0]    [0 0 0 0 1][X10]   [0 0 0 0 1][X5]   [0 0 0 0 1][X0]   [1]
   
              [X4]    [1 0 0 0 0][X4]   [1]
              [X3]    [0 1 0 0 0][X3]   [0]
   [activate]([X2]) = [0 0 1 0 0][X2] + [0]
              [X1]    [0 0 0 1 0][X1]   [0]
              [X0]    [0 0 0 0 1][X0]   [0]
   
          [0]
          [1]
   [tt] = [0]
          [2]
          [2]
   
         [X14]  [X9]  [X4]    [1 1 0 0 1][X14]   [1 0 0 2 3][X9]   [1 0 0 0 0][X4]   [0]
         [X13]  [X8]  [X3]    [0 0 0 0 0][X13]   [0 0 0 0 0][X8]   [0 0 0 0 0][X3]   [0]
   [U12]([X12], [X7], [X2]) = [0 0 0 2 2][X12] + [0 0 0 1 2][X7] + [0 0 0 0 1][X2] + [0]
         [X11]  [X6]  [X1]    [0 0 0 1 0][X11]   [0 0 0 0 1][X6]   [0 0 0 1 2][X1]   [0]
         [X10]  [X5]  [X0]    [0 0 0 0 0][X10]   [0 0 0 0 1][X5]   [0 0 0 0 1][X0]   [3]
   
   
   Qed