Papers by Francesco Vargiu
Journal of Graph Algorithms and Applications, 2000
We present a method for constructing orthogonal drawings of graphs of maximum degree six in three... more We present a method for constructing orthogonal drawings of graphs of maximum degree six in three dimensions. The method is based on generating the final drawing through a sequence of steps, starting from a "degenerate" drawing. At each step the drawing "splits" into two pieces and finds a structure more similar to its final version. Also, we test the effectiveness of our approach by performing an experimental comparison with several existing algorithms.
SIAM Journal on Computing, 1998
We deal with the problem of constructing the orthogonal drawing of a graph with the minimum numbe... more We deal with the problem of constructing the orthogonal drawing of a graph with the minimum number of bends along the edges. The problem has been recently shown to be NPcomplete in the general case. In this paper we introduce and study the new concept of spirality, which is a measure of how an orthogonal drawing is "rolled up," and develop a theory on the interplay between spirality and number of bends of orthogonal drawings. We exploit this theory to present polynomial time algorithms for two significant classes of graphs: series-parallel graphs and 3-planar graphs. Series-parallel graphs arise in a variety of problems such as scheduling, electrical networks, data-flow analysis, database logic programs, and circuit layout. Also, they play a central role in planarity problems. Furthermore, drawings of 3-planar graphs are a classical field of investigation.
Software: Practice and Experience, 2000
Graph drawing plays an important role in the solution of many information visualization problems.... more Graph drawing plays an important role in the solution of many information visualization problems. Most of the graph drawing algorithms are accompanied by a theoretical analysis of their characteristics, but only extensive experimentations can assess the practical performance of graph drawing algorithms in reallife applications. In this paper, we describe the results of some of the most popular experimental studies on graph drawing algorithms. Each study presents an in-depth comparative analysis on a specific class of algorithms, namely, algorithms for orthogonal drawings, interactive algorithms, algorithms for hierarchical drawings, and force-directed and randomized algorithms.
Drawing Directed Acyclic Graphs: An Experimental Study
In this paper we present an extensive experimental study comparing four general-purpose graph dra... more In this paper we present an extensive experimental study comparing four general-purpose graph drawing algorithms. The four algorithms take as input general graphs (with no restrictions whatsoever on connectivity, planarity, etc.) and construct orthogonal grid drawings, which are widely used in software and database visualization applications. The test data (available by anonymous ftp) are 11,582 graphs, ranging from 10 to 100 vertices, which have been generated from a core set of 112 graphs used in "real-life" software engineering and database applications. The experiments
An Experimental Comparison of Three Graph Drawing Algorithms (Extended Abstract)
In this paper we present an extensive experimental study...
3DCube: a Tool for Three Dimensional
Abstract. In this paper we describe a tool that is a general frame for the three-dimensional repr... more Abstract. In this paper we describe a tool that is a general frame for the three-dimensional representation of graphs, especially devoted to the algorithms evaluation, refinement and development. 3DCube (3D Diagram Drawer) offers innovative features in the user interaction and contains a set of three-dimensional algorithms both taken from the literature and proposed by the authors.
3DCube: a Tool for Three Dimensional Graph Drawing
We present a method for constructing orthogonal drawings of graphs of maximum degree six in three... more We present a method for constructing orthogonal drawings of graphs of maximum degree six in three dimensions. The method is based on generating the final drawing through a sequence of steps, starting from a "degenerate" drawing. At each step the drawing "splits" into two pieces and finds a structure more similar to its final version. Also, we test the effectiveness of our approach by performing an experimental comparison with several existing algorithms.
In this paper we consider the class of directed acyclic graphs (DAGs), and present the results of... more In this paper we consider the class of directed acyclic graphs (DAGs), and present the results of an experimental study on four drawing algorithms specifically developed for DAGs. Our study is conducted on two large test suites of DAGs and yields more than 30 charts comparing the performance of the drawing algorithms with respect to several quality measures, including area, crossings, bends, and aspect ratio. The algorithms exhibit various trade-offs with respect to the quality measures, and none of them clearly outperforms the others.
Reverse engineering, reuse reengineering and visual environment: the VAPS project
Spirality of orthogonal representations and optimal drawings of series-parallel graphs and 3-planar graphs (extended abstract)
Lecture Notes in Computer Science, 1993
An orthogonal drawing of a graph is a planar drawing such that all the edges are polygonal chains... more An orthogonal drawing of a graph is a planar drawing such that all the edges are polygonal chains of horizontal and vertical segments. Finding the planar embedding of a planar graph such that its orthogonal drawing has the minimum number of bends is a fundamental open problem in graph drawing. This paper provides the first partial solution to the problem.
GD-Workbench: A system for prototyping and testing graph drawing algorithms
Lecture Notes in Computer Science, 1996
We present a tool for quick prototyping and testing graph drawing algorithms. The user interacts ... more We present a tool for quick prototyping and testing graph drawing algorithms. The user interacts with the system through a diagrammatic interface. Algorithms are visually displayed as directed paths in a graph. The user can specify an algorithm by suitably combining the edges of a path. The implementation exploits the powerful functionalities of Diagram Server and has been experimented both
Orthogonal drawings with the minimum number of bends
Spirality of Orthogonal Representations and Optimal Drawings of Series-Parallel Graphs and 3-Planar Graphs
An orthogonal drawing of a graph is a planar drawing such that all the edges are polygonal chains... more An orthogonal drawing of a graph is a planar drawing such that all the edges are polygonal chains of horizontal and vertical segments. Finding the planar embedding of a planar graph such that its orthogonal drawing has the minimum number of bends is a fundamental open problem in graph drawing. This paper provides the first partial solution to the problem.
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Papers by Francesco Vargiu