crossing lemma

The crossing number of a graph (http://planetmath.org/Graph) $G$ with $n$ vertices (http://planetmath.org/Graph) and $m\\geq 4n$ edges (http://planetmath.org/Graph) is

\\operatorname{cr}(G)\\geq\\frac{1}{64}\\frac{m^{3}}{n^{2}}.

随便看

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