The four pigs are so placed, each in a separate sty, that although every
one of the thirty-six sties is in a straight line (either horizontally,
vertically, or diagonally), with at least one of the pigs, yet no pig is
in line with another. In how many different ways may the four pigs be
placed to fulfil these conditions? If you turn this page round you get
three more arrangements, and if you turn it round in front of a mirror
you get four more. These are not to be counted as different arrangements.
[Illustration]