Drawing graphs is an important problem that combines flavors of computational geometry and graph theory. Applications can be found in a variety of areas including circuit layout, network management, software engineering, and graphics. The main contributions of this paper can be summarized as follows: ffl We devise a model for dynamic graph algorithms, based on performing queries and updates on an implicit representation of the drawing, and we show its applications. ffl We present several efficient dynamic drawing algorithms for trees, series-parallel digraphs, planar st-digraphs, and planar graphs. These algorithms adopt a variety of representations (e.g., straight-line, polyline, visibility), and update the drawing in a smooth way.

Association rules, introduced by Agrawal, Imielinski, and Swami, are rules of the form "for 90 % of the rows of the relation, if the row has value 1 in the columns in set W , then it has 1 also in column B". Efficient methods exist for discovering association rules from large collections of data. The number of discovered rules can, however, be so large that browsing the rule set and finding interesting rules from it can be quite difficult for the user. We show how a simple formalism of rule templates makes it possible to easily describe the structure of interesting rules. We also give examples of visualization of rules, and show how a visualization tool interfaces with rule templates. 1 Introduction Data mining (knowledge discovery in databases) is a field of increasing interest combining databases, artificial intelligence, and machine learning. The purpose of data mining is to facilitate understanding large amounts of data by discovering interesting regularities or exceptions (see e...

This paper presents a novel approach to assist the user in exploring appropriate transfer functions for the visualization of volumetric datasets. The search for a transfer function is treated as a parameter optimization problem and addressed with stochastic search techniques. Starting from an initial population of (random or pre-defined) transfer functions, the evolution of the stochastic algorithms is controlled by either direct user selection of intermediate images or automatic fitness evaluation using user-specified objective functions. This approach essentially shields the user from the complex and tedious "trial and error" approach, and demonstrates effective and convenient generation of transfer functions.

We describe Gevol, a system that visualizes the evolution of software using a novel graph drawing technique for visualization of large graphs with a temporal component. Gevol extracts information about a Java program stored within a CVS version control system and displays it using a temporal graph visualizer. This information can be used by programmers to understand the evolution of a legacy program: Why is the program structured the way it is? Which programmers were responsible for which parts of the program during which time periods? Which parts of the program appear unstable over long periods of time and may need to be rewritten? This type of information will complement that produced by more static tools such as source code browsers, slicers, and static analyzers. 1

. We demonstrate the H3Viewer graph drawing library, which can be run from a standalone program or in conjunction with other programs such as SGI's Site Manager application. Our layout and drawing algorithms support interactive navigation of large graphs up to 100,000 edges. We present an adaptive drawing algorithm with a guaranteed frame rate. Both layout and navigation occur in 3D hyperbolic space, which provides a view of a large neighborhood around an easily changeable point of interest. We find an appropriate spanning tree to use as the backbone for fast layout and uncluttered drawing, and non-tree links can be displayed on demand. Our methods are appropriate when node or link annotations can guide the choice of a good parent from among all of the incoming links. Such annotations can be constructed using only a small amount of domain-specific knowledge, thus rendering tractable many graphs which may seem rather densely connected at first glance. 1 Motivation and Context Software s...

. Generating incrementally stable layouts is important for visualizing dynamic graphs in many applications. This paper describes DynaDAG, a new heuristic for incremental layout of directed acyclic graphs drawn as hierarchies, and its application in the DynaGraph system. 1 Introduction Effective techniques have been developed for some important families of graph layouts, such as hierarchies, planar embeddings, orthogonal grids and forced-directed (spring) models [1]. These techniques have been incorporated in practical user interfaces that display static diagrams of relationships between objects [19, 18, 17]. Static diagrams are not completely satisfactory because in many situations, the displayed graphs can change. Three common scenarios are: Manual editing. Most interactive graph drawing systems allow users to manually insert and delete nodes and edges. Layouts must be updated dynamically to reflect such changes. Browsing large graphs. When only static layout is available, browsin...

ions through Manipulation of a Program Visualization A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Computer Science by Robert William Bowdidge Committee in charge: Professor William G. Griswold, Chair Professor Edwin Hutchins Professor Keith Marzullo Professor Joseph Pasquale Professor Richard N. Taylor Copyright Robert William Bowdidge, 1995 All rights reserved. The dissertation of Robert William Bowdidge is approved, and it is acceptable in quality and form for publication on microfilm: Chair University of California, San Diego 1995 iii For Christine iv TABLE OF CONTENTS Signature Page : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : iii Dedication : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : iv Table of Contents : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : v List of Figures : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : ix List of Tabl...

Abstract not found

Restructuring software to improve its design can lower software maintenance costs. One problem in restructuring is planning out the redesign. The star diagram manipulable visualization can help a programmer redesign a program based on abstract data types. However, the underlying meaning-preserving transformational support for restructuring is costly to provide.

Given a graph G and a drawing or layout of G, it is sometimes desirable to alter or adjust the layout. The challenging aspect of designing layout adjustment algorithms is to maintain a user's mental picture of the original layout. We present a new approach to layout adjustment called cluster busting in anchored graph drawing. We then give two algorithms as examples of this approach. The goals of cluster busting in anchored graph drawing are to more evenly distribute the nodes of the graph in a drawing window while maintaining the user's mental picture of the original drawing. We present simple and eÆcient iterative heuristics to accomplish these goals. We formally de ne some measures of distribution and similarity and give empirical results based on these measures to quantify our methods. The theoretical analysis of our heuristics presents a formidable challenge, thus justifying our empirical analysis. Communicated by G. Di Battista: submitted April 1996; revised March 1998. Research...