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(111) 5

Part of 1986 Tournament Of Towns

Problems(1)

TOT 111 1986 Spring J5 20 football teams in a tournament

Source:

8/29/2019
2020 football teams take part in a tournament . On the first day all the teams play one match . On the second day all the teams play a further match . Prove that after the second day it is possible to select 1010 teams, so that no two of them have yet played each other.
( S . A . Genkin)
Tournamentcombinatorics