Every student is sitting next to a friend on both sides
Source: Turkey TST 2009, Problem 6
April 5, 2009
combinatorics unsolvedcombinatorics
Problem Statement
In a class of some students are friends. In this class any n \minus{} 1 students can be seated in a round table such that every student is sitting next to a friend of him in both sides, but students can not be seated in that way. Prove that the minimum value of is .