Heuristics and pedigrees for drawing directed graphs

We describe here a collection of heuristics for producing “nice”drawings of directed graphs, and a simple dual-mode software tool for testing and evaluating them. In playing mode, the heuristics are applied in random sequence over a set of drawings, in the manner of an asynchronous team (A-team). As new drawings are added to the set, others are deleted based on a multi-valued aesthetic evaluation function. By inspecting the “pedigree” of the best solutions found in playing mode, the user can obtain insights into the best order in which the heuristics should be applied. Then the user can test these insights in the working mode, where the heuristics are applied in a fixed sequence. Some of the heuristics that we describe here are similar to the steps of Sugiyama's D-ABDUCTOR graph-drawing package; and indeed we can obtain results similar to those of D-ABDUCTOR, by applying our heuristics in the proper sequence.