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MathNet 2016-part-07 — 182 problems (EN–VI) Question 135

Math Olympiad Vault · MathNet 2016-part-07 — 182 problems (EN–VI)

Question 135

We want to design a new chess piece, the American, with the property that (i) the American can never attack itself, and (ii) if an American $A_{1}$ attacks another American $A_{2}$, then $A_{2}$ also attacks $A_{1}$. Let $m$ be the number of squares that an American attacks when placed in the top left corner of an $8$ by $8$ chessboard. Let $n$ be the maximal number of Americans that can be placed on the $8$ by $8$ chessboard such that no Americans attack each other, if one American must be in the top left corner. Find the largest possible value of $m n$.
Proposed by: Kevin Yang