Structure for playing 4 dimensional tic-tac-toe [knots & crosses]. - ca1953. - Drawing : lead pencil, coloured pencil : 26 x 20 cm
The following comments are written in the margins:
Center squares not used as they are common to too many diagonals - the person who places a mark in the very center one is sure to win.
4 rectangular directions [verticle, horizontal, receding verticle, receding horizontal]
Simple diagonal directions
Double diagonal directions
Triple diagonal directions