IMO 1964 Problem 4
- Day 2
Seventeen people correspond by mail with one another-each one with all the rest. In their letters only three different topics are discussed. each pair of correspondents deals with only one of these topics. Prove that there are at least three people who write to each other about the same topic.
Official text Transcription from AI-MO AoPS, checked word for word against the official paper. Quoted with source.
Official text: IMO 1964 official English paper, page 1.
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.