Proportional contact representations of 4-connected planar graphs

  • Authors:
  • Md. Jawaherul Alam;Stephen G. Kobourov

  • Affiliations:
  • Department of Computer Science, University of Arizona, Tucson, AZ;Department of Computer Science, University of Arizona, Tucson, AZ

  • Venue:
  • GD'12 Proceedings of the 20th international conference on Graph Drawing
  • Year:
  • 2012

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Abstract

In a contact representation of a planar graph, vertices are represented by interior-disjoint polygons and two polygons share a non-empty common boundary when the corresponding vertices are adjacent. In the weighted version, a weight is assigned to each vertex and a contact representation is called proportional if each polygon realizes an area proportional to the vertex weight. In this paper we study proportional contact representations of 4-connected internally triangulated planar graphs. The best known lower and upper bounds on the polygonal complexity for such graphs are 4 and 8, respectively. We narrow the gap between them by proving the existence of a representation with complexity 6. We then disprove a 10-year old conjecture on the existence of a Hamiltonian canonical cycle in a 4-connected maximal planar graph, which also implies that a previously suggested method for constructing proportional contact representations of complexity 6 for these graphs will not work. Finally we prove that it is NP-hard to decide whether a 4-connected planar graph admits a proportional contact representation using only rectangles.