(k,p)-Planarity: A Relaxation of Hybrid Planarity

Emilio Di Giacomo; William J. Lenhart; Giuseppe Liotta; Timothy W. Randolph; Alessandra Tappini

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arXiv · 1806.11413

(k,p)-Planarity: A Relaxation of Hybrid Planarity

Emilio Di Giacomo·William J. Lenhart·Giuseppe Liotta·Timothy W. Randolph·Alessandra Tappini

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Abstract

We present a new model for hybrid planarity that relaxes existing hybrid representations. A graph $G = (V,E)$ is $(k,p)$-planar if $V$ can be partitioned into clusters of size at most $k$ such that $G$ admits a drawing where: (i) each cluster is associated with a closed, bounded planar region, called a cluster region; (ii) cluster regions are pairwise disjoint, (iii) each vertex $v \in V$ is identified with at most $p$ distinct points, called \emph{ports}, on the boundary of its cluster region; (iv) each inter-cluster edge $(u,v) \in E$ is identified with a Jordan arc connecting a port of $u$ to a port of $v$; (v) inter-cluster edges do not cross or intersect cluster regions except at their endpoints. We first tightly bound the number of edges in a $(k,p)$-planar graph with $p<k$. We then prove that $(4,1)$-planarity testing and $(2,2)$-planarity testing are NP-complete problems. Finally, we prove that neither the class of $(2,2)$-planar graphs nor the class of $1$-planar graphs contains the other, indicating that the $(k,p)$-planar graphs are a large and novel class.

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Emilio Di Giacomo, William J. Lenhart, Giuseppe Liotta, Timothy W. Randolph, Alessandra Tappini. 2018-06-29. (k,p)-Planarity: A Relaxation of Hybrid Planarity. https://arxiv.org/abs/1806.11413

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