OBM 1999 Problem 3
How many coins can be placed on a board (each at the center of its square, at most one per square) so that no four coins form a rectangle with sides parallel to the sides of the board?
Dataset text AI-MO AoPS. Quoted with source.
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.
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