Drawing Series-Parallel Graphs on Restricted Integer 3D Grids
A k-track drawing is a crossing-free 3D straight-line grid drawing of a graph G on a set of k parallel lines called tracks. The minimum value of k for which G admits a k-track drawing is called the track number of G. In the existing literature a lower bound of five and an upper bound of fifteen are known for the track number of series-parallel graph. In this paper we reduce this gap for a large subclass of series-parallel graph for which the lower bound remains five but we show an upper bound of eight. We also describe a linear time drawing algorithm that computes a 3D straight-line grid drawing of these graphs in volume 4 × 4 × 2n.