Imbalance is fixed parameter tractable

  • Authors:
  • Daniel Lokshtanov;Neeldhara Misra;Saket Saurabh

  • Affiliations:
  • University of California San Diego, San Diego, USA;Institute of Mathematical Sciences, Chennai, India;Institute of Mathematical Sciences, Chennai, India

  • Venue:
  • Information Processing Letters
  • Year:
  • 2013

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Abstract

In the Imbalance Minimization problem we are given a graph G=(V,E) and an integer b and asked whether there is an ordering v"1...v"n of V such that the sum of the imbalance of all the vertices is at most b. The imbalance of a vertex v"i is the absolute value of the difference between the number of neighbors to the left and right of v"i. The problem is also known as the Balanced Vertex Ordering problem and it finds many applications in graph drawing. We show that this problem is fixed parameter tractable and provide an algorithm that runs in time 2^O^(^b^l^o^g^b^)@?n^O^(^1^). This resolves an open problem of Kara et al. [On the complexity of the balanced vertex ordering problem, in: COCOON, in: Lecture Notes in Comput. Sci., vol. 3595, 2005, pp. 849-858].