KöMaL 2011 C1071
The forum of this journal on the internet has exactly 1000 registered members. Each member sends an e-mail to one other member. Prove that it is possible to select a group of 334 members such that within the group no one sent an e-mail to anyone else.
Official text KöMaL. 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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