Stephen Wismath -- Research Interests

Computational Geometry

Visibility:

• Characterizing Bar Line-of-Sight Graphs,
  Wismath, S.,
  Proceedings of the Symposium on Computational Geometry, Baltimore, 1985, pp. 147-152.
  
• Determining bar-representability for ordered weighted graphs,
  Kirkpatrick, D.; Wismath, S. ,
  Computational Geometry: Theory and Applications, Vol 6, No. 2, May 1996, pp. 99-122.
  

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• Computing the Full Visibility Graph of a Set of Line Segments,
  Wismath,S.,
  Information Processing Letters, 42, July 1992, pp. 257-261.

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• Visibility Stabs and Depth-First Spiralling on Line Segments in Output Sensitive Time,
  Keil, M.; Mount, D.; Wismath, S.;
  Int. J. of Computational Geometry and Applications, Vol 10, No. 5, Oct. 2000, pp.535-552.

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• Point and Line Segment Reconstruction from Visibility Information,
  Wismath, S.,
  Int. J. of Computational Geometry and Applications, Vol. 10, No. 2 (2000) pp. 189-200.
  

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• Orthogonal Polygon Reconstruction from Stabbing Information,
  Jackson, L.; Wismath, S.,
  Computational Geometry: Theory and Applications, Vol. 23, No. 1, pp. 69-83, July 2002.
  

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• Properties of Arrangement Graphs,
  Bose, J.; Everett, H.; Wismath, S.;
  Int. J. of Computational Geometry and Applications -- accepted, to appear.
  

Graph Drawing

• Bounds for Orthogonal 3-D Graph Drawing,
  Biedl, T.; Shermer, T.; Whitesides, S.; Wismath, S.;
  Journal of Graph Algorithms and Applications , (special issue on new trends in Graph Drawing) Vol. 3, No. 4, 1999, pp. 63-79.
  

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• Fully Dynamic Three-Dimensional Orthogonal Graph Drawing
  Closson, M.; Gartshore, S.; Johansen, J.; Wismath, S.;
  Journal of Graph Algorithms and Applications, Vol 5, No. 2, 2001 pp. 1-34.
  

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• Straight-Line Drawings on Restricted Integer Grids in Two and Three Dimensions;
  Felsner, S.; Liotta, G.; Wismath, S.;
  As submitted to (special issue) Journal of Graph Algorithms and Applications, (JGAA) (Jan 2003) pp.1--33.
  Accepted and presented at Graph Drawing 2001 in Vienna, Sept.23-26. Springer-Verlag Lecture Notes in Computer Science 2265, pp. 328-342.

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• The k-lines Drawability Problem for Series-Parallel Graphs ;
  Di Giacomo, Liotta, Wismath;
  U of Lethbridge Technical Report TR-CS-02-02, pp. 1-32
  accepted and presented at CCCG02, August 12-14, 2002.
  
• Book Embeddability of Series-Parallel Digraphs ;
  Di Giacomo, Didimo, Liotta, Wismath;
  Submitted to Algorithmica.
  Accepted and presented at Graph Drawing 2002, Irvine, August 26-28, 2002.
  
• 3-Dimensional Straight-Line Graph Drawing ,
  S. Wismath,
  As presented at the Journées de Géométrie Algorithmique 2002 held in Obernai, France, Oct 14-18, 2002.

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• Drawing Planar Graphs on a Curve ;
  Di Giacomo, Didimo, Liotta, Wismath;
  Accepted and presented at WG2003 - 29th Workshop on Graph Theoretic Concepts in Computer Science, June 2003
  

Software and Scientific Visualization

• VisPak: A Package of Visibility Algorithms Written in LEDA
  Jackson, L.; Pinto, H.; Wismath, S. ,
  Technical Report UL-CS-95-1, 1995.
• ArrangePak, OrthoPak and VisPak 2.0 ,
  Closson, M.; Everett, H; Gartshore, S.; Wismath S;
  University of Lethbridge Technical Report TR-CS-01-98, 1998.
• GLuskap: Visualization and Manipulation of Graph Drawings in 3D ;
  Dyck, B.; Joevenazzo, J.; Nickle, E.; Wilsdon, J.; Wismath, S.
  Poster/demo accepted at Graph Drawing 2003, September 2003, Perugia, Italy.
  
• ArrangePak3D ; Dufresne, R.; Nickle, E.; Wismath, S.

Program Committees

I have served recently on the program committees for:

• Graph Drawing 2005 Limerick Ireland in September 2005.
• the 17th Canadian Conference on Computational Geometry U. of Windsor in Aug. 2005.
• The 2004 International Conference on Computational Science and its Applications (ICCSA2004) held in Italy in May, 2004.
• Graph Drawing 2003 held in Perugia, Italy September 21-24, 2003.
• Canadian Conference on Computational Geometry 2003 held in Halifax in August, 2003.
• The 2003 International Conference on Computational Science and its Applications (ICCSA2003) held in Montreal in May, 2003.
• 14th Canadian Conference on Computational Geometry, hosted in Lethbridge August 12-14, 2002.
• Graph Drawing 2000 held in Williamsburg, Virginia, Sept. 20-23, 2000.
• the 12th Canadian Conference on Computational Geometry held at the U. of New Brunswick in Aug. 2000.

Graduate Students:

LillAnne Jackson -- graduated in 1996 -- currently doing a PhD in CS at the U. of Calgary.

Elpseth Nickle -- started Jan 2003 (co-supervised with Dr. D. Gaur).

Sebastian Hanlon -- started Sept. 2004.

Undergraduate summer students:

In the last several years, I have hired the following undergraduate students to work on research projects:
Helen Pinto, Michael Closson, Shane Gartshore, John Johansen, Breanne Dyck, Jill Joevenazzo, Jon Wilsdon, Sebastian Hanlon, Ray Dufresne, Kim Hansen.

Summer of 2005: Carrie Wang, Ethan Kim

Open Problems:

• Can all outerplanar graphs be drawn in 2D in O(n) area?
• Can all planar graphs be drawn in 3D in O(n) volume?