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The most kings that cannot attack each other

chessboardextremalpackingkings

A king attacks the eight squares surrounding it.

What is the largest number of kings that can be placed on an 8 by 8 chessboard so that no two attack each other? Prove the bound, and say what happens on a 7 by 7 board.

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Divide the board into 2 by 2 blocks. How many kings can one block hold?

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