Strict confluent drawing
Eppstein, D., Holten, D., Löffler, M., Nöllenburg, M., Bettina Speckmann, Verbeek, K.A.B. · TU/e Research Portal · 2016
We define strict confluent drawing, a form of confluent drawing in which the existence of an edge is indicated by the presence of a smooth path through a system of arcs and junctions (without crossings), and in which such a path, if it exists, must be unique. We prove that it is NP-complete to determine whether a given graph has a strict confluent drawing but polynomial to determine whether it has an outerplanar strict confluent drawing with a fixed vertex ordering (a drawing within a disk, with the vertices placed in a given order on the boundary).