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