Core Concepts
The asymptotic mutual information between an unknown signal belonging to a high-dimensional compact group and its noisy pairwise observations can be approximated by the mutual information in a simpler linear observation model. This result enables the characterization of the information-theoretic limits of estimation in group synchronization and quadratic assignment problems.
Abstract
The content presents a general framework for studying Bayesian inference problems where the unknown parameter of interest is an element of a high-dimensional compact group, given noisy pairwise observations of a featurization of this parameter.
Key highlights:
- The authors establish a quantitative comparison between the signal-observation mutual information in the original quadratic observation model and that in a simpler linear observation model. This is done using interpolation methods.
- For group synchronization problems, the authors provide a rigorous proof of a replica formula for the asymptotic mutual information and Bayes-optimal minimum mean-squared error (MMSE). They analyze the optimization landscape of the replica potential to characterize the information-theoretic limits of inference.
- For quadratic assignment problems, the authors show that the asymptotic mutual information coincides with that in a low-rank matrix estimation model with i.i.d. signal prior, under a bounded signal-to-noise regime.
The authors also establish an overlap concentration result, showing that the posterior overlap between the estimated signal and the true signal concentrates near the set of near-maximizers of the replica potential.