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Sharp large deviations and concentration inequalities for the number of descents in a random permutation

Published online by Cambridge University Press:  05 January 2024

Bernard Bercu*
Affiliation:
Université de Bordeaux, Institut de Mathématiques de Bordeaux
Michel Bonnefont*
Affiliation:
Université de Bordeaux, Institut de Mathématiques de Bordeaux
Adrien Richou*
Affiliation:
Université de Bordeaux, Institut de Mathématiques de Bordeaux
*
*Postal address: Université de Bordeaux, Institut de Mathématiques de Bordeaux, UMR CNRS 5251, 351 Cours de la Libération, 33405 Talence cedex, France.
*Postal address: Université de Bordeaux, Institut de Mathématiques de Bordeaux, UMR CNRS 5251, 351 Cours de la Libération, 33405 Talence cedex, France.
*Postal address: Université de Bordeaux, Institut de Mathématiques de Bordeaux, UMR CNRS 5251, 351 Cours de la Libération, 33405 Talence cedex, France.

Abstract

The goal of this paper is to go further in the analysis of the behavior of the number of descents in a random permutation. Via two different approaches relying on a suitable martingale decomposition or on the Irwin–Hall distribution, we prove that the number of descents satisfies a sharp large-deviation principle. A very precise concentration inequality involving the rate function in the large-deviation principle is also provided.

Type
Original Article
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of Applied Probability Trust

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