Problem 4

Part of the 12th XMO

Problems(1)

Source: 12th XMO

n,

使得对任意有

{1000}

个顶点且每个顶点度均为

{4}

G,

都一定可以从中取掉

{n}

,

{G}

变为二部图

.

graph theoryxmocombinatorics