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QEDMO
2007 QEDMO 5th
7
7
Part of
2007 QEDMO 5th
Problems
(1)
in 20 people, each person sends a letter to 10 of the others
Source: Norwegian Mathematical Olympiad 1994 - Abel Competition p4a
2/11/2020
In a group of
20
20
20
people, each person sends a letter to
10
10
10
of the others. Prove that there are two persons who send a letter to each other.
combinatorics