An Alternative Proof for the Expected Number of Distinct Consecutive Patterns in a Random Permutation

Let $\pi_n$ be a uniformly chosen random permutation on $[n]$. Using an analysis of the probability that two overlapping consecutive $k$-permutations are order isomorphic, the authors of a recent paper showed that the expected number of distinct consecutive patterns of all lengths $k\in\{1,2,\ldots,...

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Bibliographic Details
Main Authors: Anant Godbole, Hannah Swickheimer
Format: Article
Language:English
Published: Discrete Mathematics & Theoretical Computer Science 2024-05-01
Series:Discrete Mathematics & Theoretical Computer Science
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Online Access:http://dmtcs.episciences.org/12458/pdf
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Summary:Let $\pi_n$ be a uniformly chosen random permutation on $[n]$. Using an analysis of the probability that two overlapping consecutive $k$-permutations are order isomorphic, the authors of a recent paper showed that the expected number of distinct consecutive patterns of all lengths $k\in\{1,2,\ldots,n\}$ in $\pi_n$ is $\frac{n^2}{2}(1-o(1))$ as $n\to\infty$. This exhibited the fact that random permutations pack consecutive patterns near-perfectly. We use entirely different methods, namely the Stein-Chen method of Poisson approximation, to reprove and slightly improve their result.
ISSN:1365-8050