Variables:
X1::[1..8]
X2::[1..8]
X3::[1..8]
X4::[1..8]
X5::[1..8]
X6::[1..8]
X7::[1..8]
X8::[1..8]

Constraints:
X1 != X2
X1 != X3
X1 != X4
X1 != X5
X1 != X6
X1 != X7
X1 != X8
X2 != X3
X2 != X4
X2 != X5
X2 != X6
X2 != X7
X2 != X8
X3 != X4
X3 != X5
X3 != X6
X3 != X7
X3 != X8
X4 != X5
X4 != X6
X4 != X7
X4 != X8
X5 != X6
X5 != X7
X5 != X8
X6 != X7
X6 != X8
X7 != X8
X1 != X2 + 1
X1 != X3 + 2
X1 != X4 + 3
X1 != X5 + 4
X1 != X6 + 5
X1 != X7 + 6
X1 != X8 + 7
X2 != X3 + 1
X2 != X4 + 2
X2 != X5 + 3
X2 != X6 + 4
X2 != X7 + 5
X2 != X8 + 6
X3 != X4 + 1
X3 != X5 + 2
X3 != X6 + 3
X3 != X7 + 4
X3 != X8 + 5
X4 != X5 + 1
X4 != X6 + 2
X4 != X7 + 3
X4 != X8 + 4
X5 != X6 + 1
X5 != X7 + 2
X5 != X8 + 3
X6 != X7 + 1
X6 != X8 + 2
X7 != X8 + 1
X1 != X2 - 1
X1 != X3 - 2
X1 != X4 - 3
X1 != X5 - 4
X1 != X6 - 5
X1 != X7 - 6
X1 != X8 - 7
X2 != X3 - 1
X2 != X4 - 2
X2 != X5 - 3
X2 != X6 - 4
X2 != X7 - 5
X2 != X8 - 6
X3 != X4 - 1
X3 != X5 - 2
X3 != X6 - 3
X3 != X7 - 4
X3 != X8 - 5
X4 != X5 - 1
X4 != X6 - 2
X4 != X7 - 3
X4 != X8 - 4
X5 != X6 - 1
X5 != X7 - 2
X5 != X8 - 3
X6 != X7 - 1
X6 != X8 - 2
X7 != X8 - 1
