Planar lombardi drawings of outerpaths

  • Authors:
  • Maarten Löffler;Martin Nöllenburg

  • Affiliations:
  • Dept. of Information and Computing Sciences, Utrecht University, The Netherlands;Institut für Theoretische Informatik, KIT, Germany

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

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Abstract

A Lombardi drawing of a graph is a drawingwhere edges are represented by circular arcs that meet at each vertex v with perfect angular resolution 360°/deg(v) [3]. It is known that Lombardi drawings do not always exist, and in particular, that planar Lombardi drawings of planar graphs do not always exist [1], even when the embedding is not fixed. Existence of planar Lombardi drawings is known for restricted classes of graphs, such as subcubic planar graphs [4], trees [2], Halin graphs and some very symmetric planar graphs [3]. On the other hand, all 2-degenerate graphs, including all outerplanar graphs, have Lombardi drawings, but not necessarily planar ones [3]. One question that was left open is whether outerplanar graphs always have planar Lombardi drawings or not. In this note, we report that the answer is "yes" for a more restricted subclass: the outerpaths, i.e., outerplanar graphs whose weak dual is a path. We sketch an algorithm that produces an outerplanar Lombardi drawing of any outerpath, in linear time.