Planar Confluent Orthogonal Drawings of 4-Modal Digraphs
Sabine Cornelsen and Gregor Diatzko
Vol. 27, no. 7, pp. 523-540, 2023. Regular paper.
Abstract In a planar confluent orthogonal drawing (PCOD) of a directed graph (digraph) vertices are drawn as points in the plane and edges as orthogonal polylines starting with a vertical segment and ending with a horizontal segment. Edges may overlap in their first or last segment, but must not intersect otherwise. PCODs can be seen as a directed variant of Kandinsky drawings or as planar L-drawings of subdivisions of digraphs. The maximum number of subdivision vertices in any edge is then the split complexity. A PCOD is upward if each edge is drawn with monotonically increasing y-coordinates and quasi-upward if no edge starts with decreasing y-coordinates. We study the split complexity of PCODs and (quasi-)upward PCODs for various classes of graphs.

 This work is licensed under the terms of the CC-BY license.
Submitted: April 2023.
Reviewed: July 2023.
Revised: July 2023.
Accepted: July 2023.
Final: July 2023.
Published: August 2023.
Communicated by Giuseppe Liotta
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