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HMMT 二月 2009 · TEAM2 赛 · 第 1 题

HMMT February 2009 — TEAM2 Round — Problem 1

专题
Contest Math / 竞赛数学
难度
L3
来源
HMMT

题目详情

英文原题

  1. [ 6 ] What are the chromatic numbers of each of the three graphs shown below? Draw a coloringhaving the minimum number of colors for each. Label the vertices with symbols to indicatethe color of each vertex. (For example, you may mark a vertex “R” if you wish to indicatethat it is colored red.)
解析

英文解析

  1. [ 6 ] What are the chromatic numbers of each of the three graphs shown below? Draw a coloringhaving the minimum number of colors for each. Label the vertices with symbols to indicatethe color of each vertex. (For example, you may mark a vertex “R” if you wish to indicatethat it is colored red.)
    Solution: The chromatic numbers of the three graphs are 3, 5, and 2, respectively.