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Poster

A Unified Framework for Uniform Signal Recovery in Nonlinear Generative Compressed Sensing

Junren Chen · Jonathan Scarlett · Michael Ng · Zhaoqiang Liu

Great Hall & Hall B1+B2 (level 1) #1403

Abstract: In generative compressed sensing (GCS), we want to recover a signal xRn from m measurements (mn) using a generative prior xG(B2k(r)), where G is typically an L-Lipschitz continuous generative model and B2k(r) represents the radius-r 2-ball in Rk. Under nonlinear measurements, most prior results are non-uniform, i.e., they hold with high probability for a fixed x rather than for all x simultaneously. In this paper, we build a unified framework to derive uniform recovery guarantees for nonlinear GCS where the observation model is nonlinear and possibly discontinuous or unknown. Our framework accommodates GCS with 1-bit/uniformly quantized observations and single index model as canonical examples. Specifically, using a single realization of the sensing ensemble and generalized Lasso, all xG(B2k(r)) can be recovered up to an 2-error at most ϵ using roughly O~(k/ϵ2) samples, with omitted logarithmic factors typically being dominated by logL. Notably, this almost coincides with existing non-uniform guarantees up to logarithmic factors, hence the uniformity costs very little. As part of our technical contributions, we introduce Lipschitz approximation to handle discontinuous observation models. We also develop a concentration inequality that produces tighter bound for product process whose index sets have low metric entropy. Experimental results are presented to corroborate our theory.

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