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MathNet 1996 — Part 01 Question 9

Math Olympiad Vault · MathNet 1996 — Part 01

Question 9

On an infinite checkerboard, two players alternately mark one unmarked cell. One of them uses $\times$, the other $o$. The first who fills a $2 \times 2$ square with his symbols wins. Can the player who starts always win?