Sparse Bayesian structure learning with dependent relevance determination priorsAnqi Wu, Mijung Park, OO Koyejo, & JW Pillow 
Advances in Neural Information Processing Systems 27,
eds. Z. Ghahramani, M. Welling, C. Cortes, N. D. Lawrence,
and K. Q. Weinberger, 16281636. (2014).
In many problem settings, parameter vectors are not merely sparse, but dependent in such a way that nonzero coefficients tend to cluster together. We refer to this form of dependency as “region sparsity”. Classical sparse regression methods, such as the lasso and automatic relevance determination (ARD), model parameters as independent a priori, and therefore do not exploit such dependencies. Here we introduce a hierarchical model for smooth, regionsparse weight vectors and tensors in a linear regression setting. Our approach represents a hierarchical extension of the relevance determination framework, where we add a transformed Gaussian process to model the dependencies between the prior variances of regression weights. We combine this with a structured model of the prior variances of Fourier coefficients, which eliminates unnecessary high frequencies. The resulting prior encourages weights to be regionsparse in two different bases simultaneously. We develop efficient approximate inference methods and show substantial improvements over comparable methods (e.g., group lasso and smooth RVM) for both simulated and real datasets from brain imaging.

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