Sparse solutions to an underdetermined system of linear equations via penalized Huber loss

Abstract

We investigate the computation of a sparse solution to an underdetermined system of linear equations using the Huber loss function as a proxy for the 1-norm and a quadratic error term à la Lasso. The approach is termed “penalized Huber loss”. The results of the paper allow to calculate a sparse solution using a simple extrapolation formula under a sign constancy condition that can be removed if one works with extreme points. Conditions leading to sign constancy, as well as necessary and sufficient conditions for computation of a sparse solution by penalized Huber loss, and ties among different solutions are presented.

Description
Keywords
Sparse solution, Linear system of equations, Compressed sensing, Basis pursuit, Huber loss function, Convex quadratic splines, Linear programming, l1-norm, Quadratic perturbation, Strictly convex quadratic programming
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