CH-SMO 2010 Problem 8
In a village with at least one inhabitant, there are several associations. Each inhabitant is a member of at least associations, and any two associations have at most one common member. Prove that at least associations have the same number of members.
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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