YES(?,O(n^2))
TRS:
 {
             __(X, nil()) -> X,
             __(nil(), X) -> X,
          __(__(X, Y), Z) -> __(X, __(Y, Z)),
                 U12 tt() -> tt(),
                 U11 tt() -> U12 tt(),
  isNePal __(I, __(P, I)) -> U11 tt()
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
               __(X, nil()) -> X,
               __(nil(), X) -> X,
            __(__(X, Y), Z) -> __(X, __(Y, Z)),
                   U12 tt() -> tt(),
                   U11 tt() -> U12 tt(),
    isNePal __(I, __(P, I)) -> U11 tt()
   }
  Matrix Interpretation:
   Interpretation class: triangular
             [X1]    [1 2][X1]   [1]
   [isNePal]([X0]) = [0 1][X0] + [1]
   
         [X1]    [1 2][X1]   [2]
   [U11]([X0]) = [0 1][X0] + [2]
   
          [0]
   [tt] = [3]
   
         [X1]    [1 0][X1]   [2]
   [U12]([X0]) = [0 1][X0] + [2]
   
        [X3]  [X1]    [1 2][X3]   [1 0][X1]   [0]
   [__]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [2]
   
           [2]
   [nil] = [3]
   
   
   Qed