Short and Simple Cycle Separators in Planar Graphs

We provide an implementation of an algorithm that, given a triangulated planar graph with m edges, returns a simple cycle that is a 3/4-balanced separator consisting of at most √8 m edges. An efficient construction of a short and balanced separator that forms a simple cycle is essential in numerous planar graph algorithms, for example, for computing shortest paths, minimum cuts, or maximum flows. To the best of our knowledge, this is the first implementation of such a cycle separator algorithm with a worst-case guarantee on the cycle length. We evaluate the performance of our algorithm and compare it to the planar separator algorithms recently studied by Holzer et al. [2009]. Out of these algorithms, only the Fundamental Cycle Separator (FCS) produces a simple cycle separator. However, FCS does not provide a worst-case size guarantee. We demonstrate that (1) our algorithm is competitive across all test cases in terms of running time, balance, and cycle length; (2) it provides worst-case guarantees on the cycle length, significantly outperforming FCS on some instances; and (3) it scales to large graphs.