Low-Rank Data Completion With Very Low Sampling Rate Using Newton's Method

Abstract

Newton's method is a widely applicable and empirically efficient method for finding the solution to a set of equations. The recently developed algebraic geometry analyses provide information-theoretic bounds on the sampling rate to ensure the existence of a unique completion. A remained open question from these works is to retrieve the sampled data when the sampling rate is very close to the mentioned information-theoretic bounds. This paper is concerned with proposing algorithms to retrieve the sampled data when the sampling rate is too small and close to the mentioned information-theoretic bounds. Hence, we propose a new approach for recovering a partially sampled low-rank matrix or tensor when the number of samples is only slightly more than the dimension of the corresponding manifold, by solving a set of polynomial equations using Newton's method. In particular, we consider low-rank matrix completion, matrix sensing, and tensor completion. Each observed entry contributes one polynomial equation in terms of the factors in the rank factorization of the data. By exploiting the specific structures of the resulting set of polynomial equations, we analytically characterize the convergence regions of the Newton's method for matrix completion and matrix sensing. Through extensive numerical results, we show that the proposed approach outperforms the well-known methods such as nuclear norm minimization and alternating minimization in terms of the success rate of data recovery (noiseless case) and peak signal-to-noise ratio (noisy case), especially when the sampling rate is very low.