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## Queue Layouts, Tree-Width, and Three-Dimensional Graph Drawing

### Abstract

A three-dimensional (straight-line grid) drawing of a graph represents the vertices by points in $\mathbb{Z}^3$ and the edges by non-crossing line segments. This research is motivated by the following open problem due to Felsner, Liotta, and Wismath [Graph Drawing &apos;01, Lecture Notes in Comput. Sci., 2002]: does every $n$-vertex planar graph have a three-dimensional drawing with $O(n)$ volume? We prove that this question is almost equivalent to an existing one-dimensional graph layout problem. A queue layout consists of a linear order $\sigma$ of the vertices of a graph, and a partition of the edges into queues, such that no two edges in the same queue are nested with respect to $\sigma$. The minimum number of queues in a queue layout of a graph is its queue-number. Let $G$ be an $n$-vertex member of a proper minor-closed family of graphs (such as a planar graph). We prove that $G$ has a $O(1)\times O(1)\times O(n)$ drawing if and only if $G$ has $O(1)$ queue-number. Thus the above question is almost equivalent to an open problem of Heath, Leighton, and Rosenberg [SIAM J. Discrete Math., 1992], who ask whether every planar graph has $O(1)$ queue-number? We also present partial solutions to an open problem of Ganley and Heath [Discrete Appl. Math., 2001], who ask whether graphs of bounded tree-width have bounded queue-number? We prove that graphs with bounded path-width, or both bounded tree-width and bounded maximum degree, have bounded queue-number. As a corollary we obtain three-dimensional drawings with optimal $O(n)$ volume, for series-parallel graphs, and graphs with both bounded tree-width and bounded maximum degree

Publisher: Springer
Year: 2002
OAI identifier: oai:CiteSeerX.psu:10.1.1.18.9241
Provided by: CiteSeerX