Expected number of long cycles in a random permutation
Question
For a uniformly random permutation of , let be the number of its cycles whose length exceeds . The limit equals for a rational . Find .
Short answer
. The expected number of -cycles in a random permutation of size is for every . So .
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- Counting and Combinatorics
- Expectation, Mean, and Variance
- Conditional Expectation and Variance Revisited
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