What is the largest n so that the following assertion is always true?
Assertion:
Let G be a graph with 10 vertices in which there is at least one edge among
any three vertices. Then G must contain Kn, where Kn is the complete graph
with n vertices.
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請問為甚麼解答一開始就這麼確定是K4, 然後就直接證是K4?
是要先用猜的嗎? 還是有甚麼方法可以直接先判斷是K4?