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arXiv · 1410.6828

On the number of 5-cycles in a tournament

Natasha Komarov·John Mackey
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Abstract

We find an exact formula for the number of directed 5-cycles in a tournament in terms of its edge score sequence. We use this formula to find both upper and lower bounds on the number of 5-cycles in any $n$-tournament. In particular, we show that the maximum number of 5-cycles is asymptotically equal to $\frac{3}{4}{n \choose 5}$, the expected number 5-cycles in a random tournament ($p=\frac{1}{2}$), with equality (up to order of magnitude) for almost all tournaments. Note that this means that almost all $n$-tournaments contain the maximum number of $5$-cycles.

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Natasha Komarov, John Mackey. 2017-01-16. On the number of 5-cycles in a tournament. https://arxiv.org/abs/1410.6828

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