Y by GeoKing
In a given group of people
, each member has at least two acquaintances from
. Moreover, for each cycle
in
(here '
' means that
and
are acquaintances), each
knows exactly two other members
of the cycle. Prove that there exist
such that each of them has exactly two acquaintances in
, and
have at least one common acquaintance in the group.
Authored by Mirko Petrusevski












Authored by Mirko Petrusevski
This post has been edited 2 times. Last edited by steppewolf, Feb 9, 2025, 10:35 PM