A Note on the Probability of Rectangles for Correlated Binary Strings

© 1963-2012 IEEE. Consider two sequences of ${n}$ independent and identically distributed fair coin tosses, ${X}=({X}_{1},\ldots,{X}_{n})$ and ${Y}=({Y}_{1},\ldots,{Y}_{n})$ , which are $\rho $ -correlated for each ${j}$ , i.e. $\mathbb {P}[{X}_{j}={Y}_{j}] = {\frac{1+\rho }{ 2}}$. We study the ques...

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Príomhchruthaitheoirí: Ordentlich, Or, Polyanskiy, Yury, Shayevitz, Ofer
Rannpháirtithe: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Formáid: Alt
Teanga:English
Foilsithe / Cruthaithe: Institute of Electrical and Electronics Engineers (IEEE) 2021
Rochtain ar líne:https://hdl.handle.net/1721.1/134030
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author Ordentlich, Or
Polyanskiy, Yury
Shayevitz, Ofer
author2 Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
author_facet Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Ordentlich, Or
Polyanskiy, Yury
Shayevitz, Ofer
author_sort Ordentlich, Or
collection MIT
description © 1963-2012 IEEE. Consider two sequences of ${n}$ independent and identically distributed fair coin tosses, ${X}=({X}_{1},\ldots,{X}_{n})$ and ${Y}=({Y}_{1},\ldots,{Y}_{n})$ , which are $\rho $ -correlated for each ${j}$ , i.e. $\mathbb {P}[{X}_{j}={Y}_{j}] = {\frac{1+\rho }{ 2}}$. We study the question of how large (small) the probability $\mathbb {P}[{X} \in {A}, {Y}\in {B}]$ can be among all sets ${A},{B}\subset \{0,1\}^{n}$ of a given cardinality. For sets $|{A}|,|{B}| = \Theta (2^{n})$ it is well known that the largest (smallest) probability is approximately attained by concentric (anti-concentric) Hamming balls, and this can be proved via the hypercontractive inequality (reverse hypercontractivity). Here we consider the case of $|{A}|,|{B}| = 2^{\Theta ({n})}$. By applying a recent extension of the hypercontractive inequality of Polyanskiy-Samorodnitsky (J. Functional Analysis, 2019), we show that Hamming balls of the same size approximately maximize $\mathbb {P}[{X} \in {A}, {Y}\in {B}]$ in the regime of $\rho \to 1$. We also prove a similar tight lower bound, i.e. show that for $\rho \to 0$ the pair of opposite Hamming balls approximately minimizes the probability $\mathbb {P}[{X} \in {A}, {Y}\in {B}]$.
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spelling mit-1721.1/1340302023-02-23T20:45:27Z A Note on the Probability of Rectangles for Correlated Binary Strings Ordentlich, Or Polyanskiy, Yury Shayevitz, Ofer Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science © 1963-2012 IEEE. Consider two sequences of ${n}$ independent and identically distributed fair coin tosses, ${X}=({X}_{1},\ldots,{X}_{n})$ and ${Y}=({Y}_{1},\ldots,{Y}_{n})$ , which are $\rho $ -correlated for each ${j}$ , i.e. $\mathbb {P}[{X}_{j}={Y}_{j}] = {\frac{1+\rho }{ 2}}$. We study the question of how large (small) the probability $\mathbb {P}[{X} \in {A}, {Y}\in {B}]$ can be among all sets ${A},{B}\subset \{0,1\}^{n}$ of a given cardinality. For sets $|{A}|,|{B}| = \Theta (2^{n})$ it is well known that the largest (smallest) probability is approximately attained by concentric (anti-concentric) Hamming balls, and this can be proved via the hypercontractive inequality (reverse hypercontractivity). Here we consider the case of $|{A}|,|{B}| = 2^{\Theta ({n})}$. By applying a recent extension of the hypercontractive inequality of Polyanskiy-Samorodnitsky (J. Functional Analysis, 2019), we show that Hamming balls of the same size approximately maximize $\mathbb {P}[{X} \in {A}, {Y}\in {B}]$ in the regime of $\rho \to 1$. We also prove a similar tight lower bound, i.e. show that for $\rho \to 0$ the pair of opposite Hamming balls approximately minimizes the probability $\mathbb {P}[{X} \in {A}, {Y}\in {B}]$. 2021-10-27T19:57:42Z 2021-10-27T19:57:42Z 2020 2021-03-09T20:01:17Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/134030 en 10.1109/TIT.2020.3018232 IEEE Transactions on Information Theory Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf Institute of Electrical and Electronics Engineers (IEEE) arXiv
spellingShingle Ordentlich, Or
Polyanskiy, Yury
Shayevitz, Ofer
A Note on the Probability of Rectangles for Correlated Binary Strings
title A Note on the Probability of Rectangles for Correlated Binary Strings
title_full A Note on the Probability of Rectangles for Correlated Binary Strings
title_fullStr A Note on the Probability of Rectangles for Correlated Binary Strings
title_full_unstemmed A Note on the Probability of Rectangles for Correlated Binary Strings
title_short A Note on the Probability of Rectangles for Correlated Binary Strings
title_sort note on the probability of rectangles for correlated binary strings
url https://hdl.handle.net/1721.1/134030
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