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This recent question makes me wonder: is there some known limit theorem for the distribution of the sizes of conjugacy classes in the symmetric group $S_n?$ A quick search seems to reveal nothing relevant.

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    $\begingroup$ You will maybe find some relevant information in the book "Logarithmic combinatorial structures: a probabilistic approach" by Richard Arratia,A. D. Barbour,Simon Tavaré. $\endgroup$
    – BS.
    Commented Dec 26, 2011 at 0:10
  • $\begingroup$ Probably you are already aware of the "arcsin law" (due to Vershik and Kerov) for the dual question about the limiting distribution of degrees of irreducible characters of S_n. $\endgroup$ Commented Dec 26, 2011 at 5:43
  • $\begingroup$ I deleted my answer pointing to work of Vershik, since it answers the question of a limiting distribution on partitions weighted by the size of corresponding conjugacy classes. I still think that one can get an answer to Igor's question from that. Things would be easier if the space of positive series which sum to 1 had a Lebesgue measure... $\endgroup$ Commented Dec 26, 2011 at 10:41
  • $\begingroup$ @Gjergji Thanks! I know there is a lot of work on the general probability theory of the symmetric group. I will take a look at Vershik's talk... $\endgroup$
    – Igor Rivin
    Commented Dec 26, 2011 at 12:49
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    $\begingroup$ The distribution is going to spread out quite a bit. For instance, the largest conjugacy class has cycle lengths $(n-1,1)$ and is of size $n(n-2)! = n!/(n-1)$. The number of permutations whose longest cycle has length at least $n/2$ is asymptotic to $(\log 2)n!$. $\endgroup$ Commented Dec 10, 2012 at 20:57

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