sudoku(Puzzle, Solution) :-
  Solution = Puzzle,
  Puzzle = [
    A1, A2, A3, A4, A5, A6, A7, A8, A9,
    B1, B2, B3, B4, B5, B6, B7, B8, B9,
    C1, C2, C3, C4, C5, C6, C7, C8, C9,
    D1, D2, D3, D4, D5, D6, D7, D8, D9,
    E1, E2, E3, E4, E5, E6, E7, E8, E9,
    F1, F2, F3, F4, F5, F6, F7, F8, F9,
    G1, G2, G3, G4, G5, G6, G7, G8, G9,
    H1, H2, H3, H4, H5, H6, H7, H8, H9,
    I1, I2, I3, I4, I5, I6, I7, I8, I9
  ],

  fd_domain(Puzzle, 1, 9),

  fd_all_different([A1, A2, A3, A4, A5, A6, A7, A8, A9]),
  fd_all_different([B1, B2, B3, B4, B5, B6, B7, B8, B9]),
  fd_all_different([C1, C2, C3, C4, C5, C6, C7, C8, C9]),
  fd_all_different([D1, D2, D3, D4, D5, D6, D7, D8, D9]),
  fd_all_different([E1, E2, E3, E4, E5, E6, E7, E8, E9]),
  fd_all_different([F1, F2, F3, F4, F5, F6, F7, F8, F9]),
  fd_all_different([G1, G2, G3, G4, G5, G6, G7, G8, G9]),
  fd_all_different([H1, H2, H3, H4, H5, H6, H7, H8, H9]),
  fd_all_different([I1, I2, I3, I4, I5, I6, I7, I8, I9]),

  fd_all_different([A1, B1, C1, D1, E1, F1, G1, H1, I1]),
  fd_all_different([A2, B2, C2, D2, E2, F2, G2, H2, I2]),
  fd_all_different([A3, B3, C3, D3, E3, F3, G3, H3, I3]),
  fd_all_different([A4, B4, C4, D4, E4, F4, G4, H4, I4]),
  fd_all_different([A5, B5, C5, D5, E5, F5, G5, H5, I5]),
  fd_all_different([A6, B6, C6, D6, E6, F6, G6, H6, I6]),
  fd_all_different([A7, B7, C7, D7, E7, F7, G7, H7, I7]),
  fd_all_different([A8, B8, C8, D8, E8, F8, G8, H8, I8]),
  fd_all_different([A9, B9, C9, D9, E9, F9, G9, H9, I9]),

  fd_all_different([A1, A2, A3, B1, B2, B3, C1, C2, C3]),
  fd_all_different([D1, D2, D3, E1, E2, E3, F1, F2, F3]),
  fd_all_different([G1, G2, G3, H1, H2, H3, I1, I2, I3]),

  fd_all_different([A4, A5, A6, B4, B5, B6, C4, C5, C6]),
  fd_all_different([D4, D5, D6, E4, E5, E6, F4, F5, F6]),
  fd_all_different([G4, G5, G6, H4, H5, H6, I4, I5, I6]),

  fd_all_different([A7, A8, A9, B7, B8, B9, C7, C8, C9]),
  fd_all_different([D7, D8, D9, E7, E8, E9, F7, F8, F9]),
  fd_all_different([G7, G8, G9, H7, H8, H9, I7, I8, I9]).