Near optimal solutions for maximum quasi-bicliques

  • Authors:
  • Lusheng Wang

  • Affiliations:
  • Department of Computer Science, City University of Hong Kong, Hong Kong

  • Venue:
  • COCOON'10 Proceedings of the 16th annual international conference on Computing and combinatorics
  • Year:
  • 2010

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Abstract

The maximum quasi-biclique problem has been proposed for finding interacting protein group pairs from large protein-protein interaction (PPI) networks. The problem is defined as follows: THE MAXIMUM QUASI-BICLIQUE PROBLEM: Given a bipartite graph G = (X ∪ Y,E) and a number 0 Xopt of X and a subset Yopt of Y such that any vertex x ∈ Xopt is incident to at least (1 - δ)|Yopt| vertices in Yopt, any vertex y ∈ Yopt is incident to at least (1 - δ)|Xopt| vertices in Xopt and |Xopt| + |Yopt| is maximized. The problem was proved to be NP-hard [2]. We design a polynomial time approximation scheme to give a quasi-biclique (Xa, Ya) for Xa ⊆ X and Ya ⊆ Y with |Xa| ≥ (1 - ε)|Xopt| and |Ya| ≥ (1 -ε)|Ya| such that any vertex x ∈ Xa is incident to at least (1 - δ - ε)|Ya| vertices in Ya and any vertex y ∈ Ya is incident to at least (1 - δ - ε)|Xa| vertices in Xa for any ε 0, where Xopt and Yopt form the optimal solution.