Automatic Display of Hierarchized Graphs for Computer-Aided Decision Analysis

A study of questions raised by the conception of a tool for computer-aided decision analysis that would facilitate interactive structural systems analysis and the tool itself, named GT1VX, are presented. Focusing on systems known by their elements and the relations among them, two hierarchies that apply to graphs of different types: first, rank hierarchy that is adapted to digraphs with cycles and second, number hierarchy that applies to strongly connected digraphs and to nondirected graphs are presented. Standard forms of representation of these hierarchies are defined, and the question of reducing the number of edge crossings in the drawings is studied. Finally, the software GT1VX is described. It was developed for the automatic display of graphs hierarchized according to the rank hierarchy and to the number hierarchy; GT1VX yields, within agreeable computing times, drawings in the standard forms of representation that have a limited number of edge crossings. Three real-life examples of the application of this tool are also presented.