Tag Archives: stirling numbers

Burnside’s Lemma and Polya Enumeration Theorem (2)

Posted on January 15, 2013 by limsup

[ Acknowledgement: all the tedious algebraic expansions in this article were performed by wolframalpha. ] Counting Graphs One of the most surprising applications of Burnside’s lemma and Polya enumeration theorem is in counting the number of graphs up to isomorphism. … Continue reading →

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Burnside’s Lemma and Polya Enumeration Theorem (1)

Posted on January 13, 2013 by limsup

[ Note: this article assumes you know some rudimentary theory of group actions. ] Let’s consider the following combinatorial problem. Problem. ABC is a given equilateral triangle. We wish to colour each of the three vertices A, B and C by … Continue reading →

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