Ball, W. W. Rouse (Walter William Rouse), 1850-1925 · London, Macmillan · leaf 88
Examples of Tesselated Pavements. If more than two colours are used, the problems becomeincreasingly difficult. As a simple instance of this class ofproblems I may mention one, sent to me by a correspondentwho termed it Cross-Fours, wherein sixteen cardboard squaresor tiles are used, the upper half…
Geometry · Cryptography · Ciphers
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