The Design of an Extendible Graph Editor [Paperback]

Graphs can be used to convey information about relationshipsin many applications. State transition diagrams, PERT/CPMcharts, and entity-relationship diagrams are a few examplesof many applications involving graphs. Typically, nodes inthe graph represent items in the application and the edgesrepresent the relationships among these items. A grapheditor is an interactive tool that presents a graph to theuser pictorially and allows the user to edit the graph.This monograph presents the design of an extendible grapheditor, which is a graph editor that can be adapted easilyto many different application areas. Several fundamental andrecurring problem areas associated with graph editors areinvestigated and a solution is proposed for each. The topicsinvestigated are:- Graph layout: a layout constraint mechanism is presentedwhich can easily be combined with various graph layoutalgorithms.- Graphical abstraction: a novel clustering techniquecallededge concentration is presented which can reduce theapparent complexity of the graph.- Persistence: the graph structures produced by theeditorcan be kept in long-term storage using a standardized,external format for graphs.- Extendibility: the design of the proposed graph editormakes it easy to adapt to various applications.To demonstrate their feasibility, the proposed solutionshave been incorporated into EDGE, an extendible graph editorprotoype.Graphs can be used to convey information about relationshipsin many applications. State transition diagrams, PERT/CPMcharts, and entity-relationship diagrams are a few examplesof many applications involving graphs. Typically, nodes inthe graph represent items in the application and the edgesrepresent the relationships among these items. A grapheditor is an interactive tool that presents a graph to theuser pictorially and allows the user to edit the graph.l£$