Adaptive Score-Based VAMP: Self-Tuning Hyperparameters via Tilted EM
Approximate-message-passing methods offer fast Bayesian inference for high-dimensional inverse problems, but their performance and state-evolution predictions rely on correctly specified module parameters. This paper develops an adaptive version of score-based vector approximate message passing (SC-VAMP). Each parameterized factor is updated by a local tilted expectation-maximization (EM) step that reuses the tilted moments already computed by the single-input single-output module interface. Under standard large-system state-evolution assumptions and identifiability conditions, the matched parameters form a Bayes-optimal population fixed point of the adaptive recursion. The argument is written separately for prior modules and likelihood/LMMSE modules, the latter using the Gaussian cavity induced by the VAMP transformed-error model. Numerical results for linear and one-bit Bernoulli-Gaussian compressed sensing show that the proposed updates recover near-oracle performance from strongly mismatched initializations.