English

A short note on an inequality between KL and TV

Probability 2023-08-03 v2 Statistics Theory Statistics Theory

Abstract

The goal of this short note is to discuss the relation between Kullback--Leibler divergence and total variation distance, starting with the celebrated Pinsker's inequality relating the two, before switching to a simple, yet (arguably) more useful inequality, apparently not as well known, due to Bretagnolle and Huber. We also discuss applications of this bound for minimax testing lower bounds.

Cite

@article{arxiv.2202.07198,
  title  = {A short note on an inequality between KL and TV},
  author = {Clément L. Canonne},
  journal= {arXiv preprint arXiv:2202.07198},
  year   = {2023}
}

Comments

Update: positive answer to Question 8 ("from the TFL to the BH bound"), communicated to me by Hao-Chung Cheng

R2 v1 2026-06-24T09:37:04.924Z