HMMT 二月 2000 · ADV 赛 · 第 8 题
HMMT February 2000 — ADV Round — Problem 8
题目详情
英文原题
- Ho w man y non-isomorphi graphs with 9 v erti es, with each v ertex onne ted to exa tly
6 other v erti es, are there? (Tw o graphs are isomorphi if one an relab el the v erti esof one graph to mak e all edges be exa tly the same.)
解析
英文解析
- It suÆ es to onsider the omplemen ts of the graphs, so we are lo oking for graphs with
9 v erti es, where each v ertex is onne ted to 2 others. There are 4 di eren t graphs see b elo w.
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