A Matrix Bernstein Inequality for Strong Rayleigh Distributions

Abstract

The Entropy method provides a powerful framework for proving scalar concentration inequalities by establishing functional inequalities like Poincare and log-Sobolev inequalities. These inequalities are especially useful for deriving concentration for dependent distributions coming from stationary distributions of Markov chains. In contrast to the scalar case, the study of matrix concentration inequalities is fairly recent and there does not seem to be a general framework for proving matrix concentration inequalities using the Entropy method. In this paper, we initiate the study of Matrix valued functional inequalities and show how matrix valued functional inequalities can be used to establish a kind of iterative variance comparison argument to prove Matrix Bernstein like inequalities. Strong Rayleigh distributions are a class of distributions which satisfy a strong form of negative dependence properties. We show that scalar Poincare inequalities recently established for a flip-swap markov chain considered in the work of Hermon and Salez [HS19] can be lifted to prove matrix valued Poincare inequalities. This can then be combined with the iterative variance argument to prove a version of matrix Bernstein inequality for Lipshitz matrix-valued functions for Strong Rayleigh measures.