Sparse solutions of sparse linear systems: fixed-parameter tractability and an application of complex group testing

  • Authors:
  • Peter Damaschke

  • Affiliations:
  • Department of Computer Science and Engineering, Chalmers University, Göteborg, Sweden

  • Venue:
  • IPEC'11 Proceedings of the 6th international conference on Parameterized and Exact Computation
  • Year:
  • 2011

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Abstract

A vector with at most k nonzeros is called k-sparse. We show that enumerating the support vectors of k-sparse solutions to a system Ax=b of r-sparse linear equations (i.e., where the rows of A are r-sparse) is fixed-parameter tractable (FPT) in the combined parameter r,k. For r=2 the problem is simple. For 0,1-matrices A we can also compute an O(rkr) kernel. For systems of linear inequalities we get an FPT result in the combined parameter d,k, where d is the total number of minimal solutions. This is achieved by interpeting the problem as a case of group testing in the complex model. The problems stem from the reconstruction of chemical mixtures by observable reaction products.