Jean Barbier (ICTP)
Title: Fundamental limits in structured principal component analysis and how to reach them
How does structure and statistical dependencies in the noise impact inference? This talk will answer this question in the context of the estimation of low-rank matrices corrupted by structured noise, namely noise matrices with generic spectrum, and thus dependencies among its entries. We show that the Approximate Message Passing (AMP) algorithm currently proposed in the literature for Bayesian estimation is sub-optimal. We explain the reason for this sub-optimality and as a consequence we deduce an optimal Bayesian AMP algorithm with a rigorous state evolution matching our prediction for the minimum mean-square error. Based on a joint work with Francesco Camilli, Marco Mondelli and Manuel Saenz: https://www.pnas.org/doi/abs/10.1073/pnas.2302028120?doi=10.1073/pnas.2302028120