Airport Logistics
Source: 2013 Baltic Way, Problem 9
December 31, 2013
combinatorial geometrycombinatorics unsolvedcombinatorics
Problem Statement
In a country there are airports, no three of them lying on a line. Two airports are connected by a direct flight if and only if the line passing through them divides the country in two parts, each with airports in it. Show that there are no two airports such that one can travel from the first to the second, visiting each of the airports exactly once.