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Strong NP-Hardness for Sparse Optimization with Concave Penalty Functions
Proceedings of the 34th International Conference on Machine Learning, PMLR 70:740-747, 2017.
Abstract
Consider the regularized sparse minimization problem, which involves empirical sums of loss functions for n data points (each of dimension d) and a nonconvex sparsity penalty. We prove that finding an O(nc1dc2)-optimal solution to the regularized sparse optimization problem is strongly NP-hard for any c1,c2∈[0,1) such that c1+c2<1. The result applies to a broad class of loss functions and sparse penalty functions. It suggests that one cannot even approximately solve the sparse optimization problem in polynomial time, unless P = NP.