Matrix completion from a few entries

  • Authors:
  • Raghunandan H. Keshavan;Sewoong Oh;Andrea Montanari

  • Affiliations:
  • EE Department, Stanford University, Stanford, CA;EE Department, Stanford University, Stanford, CA;EE and Statistics Departments, Stanford University, Stanford, CA

  • Venue:
  • ISIT'09 Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 1
  • Year:
  • 2009

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Abstract

Let M be an nα × n matrix of rank r ≪ n, and assume that a uniformly random subset E of its entries is observed. We describe an efficient algorithm that reconstructs M from |E| = O(r n) observed entries with relative root mean square error RMSE ≤ C(α) (nr/|E|)1/2. Further, if r = O(1) and M is sufficiently unstructured, then it can be reconstructed exactly from |E| = O(n log n) entries. This settles (in the case of bounded rank) a question left open by Candès and Recht and improves over the guarantees for their reconstruction algorithm. The complexity of our algorithm is O(|E|r log n), which opens the way to its use for massive data sets. In the process of proving these statements, we obtain a generalization of a celebrated result by Friedman-Kahn-Szemerédi and Feige-Ofek on the spectrum of sparse random matrices.