Black-box variational inference (BBVI) scales poorly for estimating a multivariate Gaussian approximation with a full covariance matrix in high-dimensional problems.
The batch-and-match (BaM) framework extends score-based BBVI and addresses the challenge of expensive storage and estimation of covariance matrices.
BaM uses specialized updates to match scores of the target density and its Gaussian approximation, instead of relying on stochastic gradient descent.
By integrating the updates with a more compact parameterization, BaM introduces a patch that projects covariance matrices into a more efficiently parameterized family of diagonal plus low rank matrices.