On the Edge-length Ratio of Outerplanar Graphs

Abstract

We show that any outerplanar graph admits a planar straightline drawing such that the length ratio of the longest to the shortest edges is strictly less than 2. This result is tight in the sense that for any $ε> 0$ there are outerplanar graphs that cannot be drawn with an edge-length ratio smaller than $2 - ε$. We also show that every bipartite outerplanar graph has a planar straight-line drawing with edge-length ratio 1, and that, for any $k \geq 1$, there exists an outerplanar graph with a given combinatorial embedding such that any planar straight-line drawing has edge-length ratio greater than k.

Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017)