Dynamic matrix rank

  • Authors:
  • Gudmund Skovbjerg Frandsen;Peter Frands Frandsen

  • Affiliations:
  • Department of Computer Science, University of Aarhus, Aabogade 34, DK-8200 Aarhus N, Denmark;Rambøll Management A/S, Olof Palmes Allé 20, DK-8200 Aarhus N, Denmark

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2009

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Abstract

We consider maintaining information about the rank of a matrix under changes of the entries. For nxn matrices, we show an upper bound of O(n^1^.^5^7^5) arithmetic operations and a lower bound of @W(n) arithmetic operations per element change. The upper bound is valid when changing up to O(n^0^.^5^7^5) entries in a single column of the matrix. We also give an algorithm that maintains the rank using O(n^2) arithmetic operations per rank one update. These bounds appear to be the first nontrivial bounds for the problem. The upper bounds are valid for arbitrary fields, whereas the lower bound is valid for algebraically closed fields. The upper bound for element updates uses fast rectangular matrix multiplication, and the lower bound involves further development of an earlier technique for proving lower bounds for dynamic computation of rational functions.