China Mathematical Olympiad 1990 problem6
Source: China Mathematical Olympiad 1990 problem6
October 21, 2013
combinatorics unsolvedcombinatorics
Problem Statement
A convex -gon and its diagonals which have no common point inside the polygon form a subdivision graph. Show that if and only if , there exists a subdivision graph that can be drawn in one closed stroke. (i.e. start from a certain vertex, get through every edges and diagonals exactly one time, finally back to the starting vertex.)