An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales

We consider the class, say ℳn,sym, of martingales Mn = X1 + ⋯ + Xn with conditionally symmetric bounded differences Xk such that |Xk | ≤ 1. We find explicitly a solution, say Dn(x), of the variational problem Dn(x) ≝ sup Mn ∈ℳn,sym ℙ {Mn ≥ x}. We show that this problem is equivalent to one when yo...

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Main Author: Dainius Dzindzalieta
Format: Article
Language:English
Published: Vilnius University Press 2023-09-01
Series:Lietuvos Matematikos Rinkinys
Subjects:
Online Access:https://www.zurnalai.vu.lt/LMR/article/view/30792
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author Dainius Dzindzalieta
author_facet Dainius Dzindzalieta
author_sort Dainius Dzindzalieta
collection DOAJ
description We consider the class, say ℳn,sym, of martingales Mn = X1 + ⋯ + Xn with conditionally symmetric bounded differences Xk such that |Xk | ≤ 1. We find explicitly a solution, say Dn(x), of the variational problem Dn(x) ≝ sup Mn ∈ℳn,sym ℙ {Mn ≥ x}. We show that this problem is equivalent to one when you want to find out the symmetric random walk with bounded length of steps which maximizes the probability to visit an interval [x;∞]. The function x \mapsto Dn(x) allows a simple description and is closely related to the binomial tail probabilities. We can interpret the result as a final and optimal upper bound ℙ{Mn ≥ x} ≤ Dn(x), x ∈ ℝ, for the tail probability ℙ {Mn ≥ x}.
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spelling doaj.art-ead85abd36a6433288745d330cdc1b182024-04-22T09:00:38ZengVilnius University PressLietuvos Matematikos Rinkinys0132-28182335-898X2023-09-0146spec.10.15388/LMR.2006.30792An exact bound for tail probabilities for a class of conditionally symmetric bounded martingalesDainius Dzindzalieta0Institute of Mathematics and Informatics We consider the class, say ℳn,sym, of martingales Mn = X1 + ⋯ + Xn with conditionally symmetric bounded differences Xk such that |Xk | ≤ 1. We find explicitly a solution, say Dn(x), of the variational problem Dn(x) ≝ sup Mn ∈ℳn,sym ℙ {Mn ≥ x}. We show that this problem is equivalent to one when you want to find out the symmetric random walk with bounded length of steps which maximizes the probability to visit an interval [x;∞]. The function x \mapsto Dn(x) allows a simple description and is closely related to the binomial tail probabilities. We can interpret the result as a final and optimal upper bound ℙ{Mn ≥ x} ≤ Dn(x), x ∈ ℝ, for the tail probability ℙ {Mn ≥ x}. https://www.zurnalai.vu.lt/LMR/article/view/30792tail probabilitiesmartingalesrandomwalkisoperimetric
spellingShingle Dainius Dzindzalieta
An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
Lietuvos Matematikos Rinkinys
tail probabilities
martingales
randomwalk
isoperimetric
title An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
title_full An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
title_fullStr An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
title_full_unstemmed An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
title_short An exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
title_sort exact bound for tail probabilities for a class of conditionally symmetric bounded martingales
topic tail probabilities
martingales
randomwalk
isoperimetric
url https://www.zurnalai.vu.lt/LMR/article/view/30792
work_keys_str_mv AT dainiusdzindzalieta anexactboundfortailprobabilitiesforaclassofconditionallysymmetricboundedmartingales
AT dainiusdzindzalieta exactboundfortailprobabilitiesforaclassofconditionallysymmetricboundedmartingales