Drawing series parallel digraphs symmetrically

In this paper we present algorithms for drawing series parallel digraphs wi th as much symmetry as possible. The first step is to compute a certain kin d of automorphism, called an "upward planar automorphism" for an input seri es parallel digraph. The next step uses these automorphisms to construct a symmetric drawing of the graph. We present several variations of the second step, with visibility drawings, "bus-orthogonal" drawings, and polyline dr awings. All algorithms run in linear time. (C) 2000 Elsevier Science B.V. A ll rights reserved.