Plane Graphs with Parity Constraints

  • Authors:
  • Oswin Aichholzer;Thomas Hackl;Michael Hoffmann;Alexander Pilz;Günter Rote;Bettina Speckmann;Birgit Vogtenhuber

  • Affiliations:
  • Institute for Software Technology, Graz University of Technology, Austria;Institute for Software Technology, Graz University of Technology, Austria;Institute for Theoretical Computer Science, ETH Zürich, Switzerland;Institute for Software Technology, Graz University of Technology, Austria;Institut für Informatik, FU Berlin, Germany;Dep. of Mathematics and Computer Science, TU Eindhoven, The Netherlands;Institute for Software Technology, Graz University of Technology, Austria

  • Venue:
  • WADS '09 Proceedings of the 11th International Symposium on Algorithms and Data Structures
  • Year:
  • 2009

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Abstract

Let S be a set of n points in general position in the plane. Together with S we are given a set of parity constraints, that is, every point of S is labeled either even or odd. A graph G on S satisfies the parity constraint of a point p *** S , if the parity of the degree of p in G matches its label. In this paper we study how well various classes of planar graphs can satisfy arbitrary parity constraints. Specifically, we show that we can always find a plane tree, a two-connected outerplanar graph, or a pointed pseudo-triangulation which satisfy all but at most three parity constraints. With triangulations we can satisfy about 2/3 of all parity constraints. In contrast, for a given simple polygon H with polygonal holes on S , we show that it is NP-complete to decide whether there exists a triangulation of H that satisfies all parity constraints.