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Derandomizing Matrix Concentration Inequalities from Free Probability

Published: January 13, 2026 | arXiv ID: 2601.08111v1

By: Robert Wang, Lap Chi Lau, Hong Zhou

Recently, sharp matrix concentration inequalities~\cite{BBvH23,BvH24} were developed using the theory of free probability. In this work, we design polynomial time deterministic algorithms to construct outcomes that satisfy the guarantees of these inequalities. As direct consequences, we obtain polynomial time deterministic algorithms for the matrix Spencer problem~\cite{BJM23} and for constructing near-Ramanujan graphs. Our proofs show that the concepts and techniques in free probability are useful not only for mathematical analyses but also for efficient computations.

Category
Computer Science:
Data Structures and Algorithms