Asymptotics of the Longest Increasing Subsequence in Random Permutations

Fuente: arXiv
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Main Author: Gupta, Mihir
Format: Preprint
Published: 2025
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author Gupta, Mihir
author_facet Gupta, Mihir
contents In this paper, we examine the asymptotic behavior of the longest increasing subsequence (LIS) in a uniformly random permutation of $n$ elements. We rely on the Robinson--Schensted--Knuth correspondence, Young tableaux, and key classical results -- including the Erdős--Szekeres theorem and the Hook Length Formula -- to demonstrate that the expected LIS length grows as $2\sqrt{n}$. We review the essential variational principles of Logan--Shepp and Vershik--Kerov, which determine the limiting shape of the associated random Young diagrams, and summarize the Baik--Deift--Johansson theorem that links fluctuations of the LIS length to the Tracy--Widom distribution. Our approach focuses on providing conceptual and intuitive explanations of these results, unifying classical proofs into a single narrative and supplying fresh visual examples, while referring the reader to the original literature for detailed proofs and rigorous arguments.
format Preprint
id arxiv_https___arxiv_org_abs_2511_00009
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Asymptotics of the Longest Increasing Subsequence in Random Permutations
Gupta, Mihir
History and Overview
Combinatorics
In this paper, we examine the asymptotic behavior of the longest increasing subsequence (LIS) in a uniformly random permutation of $n$ elements. We rely on the Robinson--Schensted--Knuth correspondence, Young tableaux, and key classical results -- including the Erdős--Szekeres theorem and the Hook Length Formula -- to demonstrate that the expected LIS length grows as $2\sqrt{n}$. We review the essential variational principles of Logan--Shepp and Vershik--Kerov, which determine the limiting shape of the associated random Young diagrams, and summarize the Baik--Deift--Johansson theorem that links fluctuations of the LIS length to the Tracy--Widom distribution. Our approach focuses on providing conceptual and intuitive explanations of these results, unifying classical proofs into a single narrative and supplying fresh visual examples, while referring the reader to the original literature for detailed proofs and rigorous arguments.
title Asymptotics of the Longest Increasing Subsequence in Random Permutations
topic History and Overview
Combinatorics
url https://arxiv.org/abs/2511.00009