Extending Partial Orthogonal Drawings

TL;DR

This paper investigates extending partial orthogonal graph drawings, providing a linear-time test for extension existence and showing NP-completeness for bend minimization.

Contribution

It introduces a linear-time algorithm for extending partial orthogonal drawings and proves NP-completeness for bend minimization problems.

Findings

Extension existence can be tested in linear time.

If extension exists, it can be drawn with O(|V(H)|) bends per edge.

Minimizing bends or fixing bends per edge is NP-complete.

Abstract

We study the planar orthogonal drawing style within the framework of partial representation extension. Let $(G,H,{\Gamma}_H )$ be a partial orthogonal drawing, i.e., G is a graph, $H\subseteq G$ is a subgraph and ${\Gamma}_H$ is a planar orthogonal drawing of H. We show that the existence of an orthogonal drawing ${\Gamma}_G$ of $G$ that extends ${\Gamma}_H$ can be tested in linear time. If such a drawing exists, then there also is one that uses $O(|V(H)|)$ bends per edge. On the other hand, we show that it is NP-complete to find an extension that minimizes the number of bends or has a fixed number of bends per edge.