                )                                                        =                                                  ∑                              k                ∈                ℤ                                      ⁢                                                            (                                      k                    -                                          0                      0                                                        )                                ⁡                                  [                                                            x                      ⁡                                              [                        k                        ]                                                              +                                          x                      ⁡                                              [                                                  k                          -                          0                                                ]                                                                              ]                                            0                                                          ∑                              k                ∈                ℤ                                      ⁢                                          [                                                      x                    ⁡                                          [                      k                      ]                                                        +                                      x                    ⁡                                          [                                              k                        -                        0                                            ]                                                                      ]                            0                                      .             