GD 2006: Graph Drawing pp 430-439

# Partitions of Graphs into Trees

• Therese Biedl
• Franz J. Brandenburg
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4372)

## Abstract

In this paper, we study the k-tree partition problem which is a partition of the set of edges of a graph into k edge-disjoint trees. This problem occurs at several places with applications e.g. in network reliability and graph theory. In graph drawing there is the still unbeaten (n − 2) ×(n − 2) area planar straight line drawing of maximal planar graphs using Schnyder’s realizers [15], which are a 3-tree partition of the inner edges. Maximal planar bipartite graphs have a 2-tree partition, as shown by Ringel [14]. Here we give a different proof of this result with a linear time algorithm. The algorithm makes use of a new ordering which is of interest of its own. Then we establish the NP-hardness of the k-tree partition problem for general graphs and k ≥ 2. This parallels NP-hard partition problems for the vertices [3], but it contrasts the efficient computation of partitions into forests (also known as arboricity) by matroid techniques [7].

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