Longest increasing cyclic run of a random permutation
ID: longest-increasing-cyclic-run-of-a-random-permutation
Arrange a uniform random permutation of distinct ordered elements around a circle, and let be the greatest number of consecutive entries that appear in increasing order. Put . Then as .
Let count increasing consecutive blocks of length . Each of the starting positions succeeds with probability , so . For , disjoint blocks have independent relative orders; blocks overlapping with a start displacement are both increasing precisely when their length- union is increasing. ThusConsequently Markov's inequality gives , while Chebyshev's inequality gives for sufficiently large . The latter uses . Both bounds vanish. These are consecutive cyclic runs; allowing arbitrary skipped entries is a different permutation statistic.
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