Greg's work:

This page is about academics. Updated November, 2009. I have a non-work page here.

You can email me at:
aloupis D0T greg 'at' gmail D0T com

As of January 2005, I am a postdoctoral researcher. Until September 2009 I mainly worked at the Département d'Informatique of Université Libre de Bruxelles, and also at Carleton University in Ottawa.
Since then I have been at Academia Sinica in Taipei, Taiwan.

I started my Ph.D. at McGill in September 2001, supervised by Godfried Toussaint
I submitted my Ph.D. thesis on January 11th and defended on March 24, 2005. The topic was Reconfigurations of Polygonal Structures. Here is an e-copy: thesis.ps (4 Mb) thesis.pdf (1Mb).

My M.Sc. thesis, submitted in March 2001, was on geometric estimators of location: G_A_thesis.ps(1 Mb) G_A_thesis.ps.gz(200 Kb) G_A_thesis.pdf(600 Kb). For an introduction to this topic online, go here.
My undergrad major was in physics. I also took part in several mobile robotics experiments.

I've taught (and been a T.A for) this graduate course: Pattern Recognition cs644. I've also been a T.A. for: Computational Geometry cs507 , Information Structures cs610 ,

My convex hull history page (which seems to have more citations than several of my papers).

Some things I've been part of:

Submitted papers

Efficient Constant-Velocity Reconfiguration of Crystalline Robots , with Sebastien Collette, Mirela Damian, Erik Demaine, Dania El-Khechen, Robin Flatland, Stefan Langerman, Joseph O'Rourke, Val Pinciu, Suneeta Ramaswami, Vera Sacristan and Stefanie Wuhrer. Journal Submission

pdf file Temporarily unavailable

Computing Signed Permutations of Polygons , with Prosenjit Bose, Erik D. Demaine, Stefan Langerman, Henk Meijer, Mark Overmars and Godfried Toussaint, Journal submission

pdf file temporarily unavailable

Triangulating and Guarding Realistic Polygons , with Prosenjit Bose, Vida Dujmovic, Chris Gray, Stefan Langerman and Bettina Speckmann , Journal submission

pdf file temporarily unavailable

Journal papers (published or accepted)

Decomposition of Multiple Coverings into More Parts , with Jean Cardinal, Sebastien Collette, Stefan Langerman, David Orden and Pedro Ramos. Accepted in Discrete and Computational Geometry (DCG), 2009.

pdf file Temporarily unavailable

Draining a Polygon -or- Rolling a Ball out of a Polygon , with Jean Cardinal, Sebastien Collette, Ferran Hurtado, Stefan Langerman and Joseph O'Rourke. Accepted in Computational Geometry: Theory and Applications (CGTA)

pdf file draining-sept2008.pdf

Highway Hull Revisited , with Jean Cardinal, Sebastien Collette, Ferran Hurtado, Stefan Langerman, Joseph O'Rourke and Belen Palop. Accepted in Computational Geometry: Theory and Applications (CGTA)

pdf file highwayhull-CGTA.pdf

Linear Reconfiguration of Cube-Style Modular Robots , with Sebastien Collette, Mirela Damian, Erik Demaine, Robin Flatland, Stefan Langerman, Joseph O'Rourke, Suneeta Ramaswami, Vera Sacristan and Stefanie Wuhrer. Accepted at: Computational Geometry: Theory and Applications (CGTA)

pdf file link to pdf

Coloring Geometric Range Spaces , with Jean Cardinal, Sebastien Collette, Stefan Langerman and Shakhar Smorodinsky. Discrete & Computational Geometry (DCG) 41, issue 2, 2009, p.348-362

pdf file link

Edge-Unfolding Nested Polyhedral Bands , with Erik D. Demaine, Stefan Langerman, Pat Morin, Joseph O'Rourke, Ileana Streinu and Godfried Toussaint, Computational Geometry: Theory and Applications (CGTA), 39, p.30-42, 2008.

pdf file band-unfolding.pdf

Reconfiguring Triangulations with Edge Flips and Point Moves , with Prosenjit Bose and Pat Morin , Algorithmica, vol.47, issue 4 (May 2007), p.367-378.

pdf file triangulations-algorithmica.pdf

Algorithms for Computing Geometric Measures of Melodic Similarity , with Thomas Fevens, Stefan Langerman, Tomomi Matsui, Antonio Mesa, Yurai Nuñez, David Rappaport and Godfried Toussaint, Computer Music Journal (CMJ), 30 (3), Fall 2006, pp.67-76.

pdf file melody.pdf

A Lower Bound for Computing Oja Depth , with Erin McLeish. Information Processing Letters 96 (4), November 2005, p.151-153.

pdf file of submitted version, September 2004: oja-depth-IPL.pdf

More classes of stuck unknotted hexagons , with Günter Ewald and Godfried Toussaint , Beiträge zur Algebra und Geometrie - Contributions to Algebra and Geometry , Vol. 45, No. 2, pp. 429-434 (2004)

PostScript file (final submitted revision, Nov 2003) locked.ps

Lower bounds for computing statistical depth , with Carmen Cortes, Francisco Gomez, Michael Soss and Godfried T. Toussaint, Computational Statistics and Data Analysis 40 (2002) 223-229.

PostScript file (final submitted revision, October 2001) StatDepth_Oct01.ps

Algorithms for Bivariate Medians and a Fermat-Torricelli Problem for Lines, with Stefan Langerman, Michael Soss and Godfried Toussaint, Computational Geometry: Theory and Applications (CGTA), Vol. 26, No. 1, August 2003, pp 69-79.

PostScript file (revised November 2002 version) mediansCGTA.ps

Conference papers (published or accepted)

Colorful Strips , with Jean Cardinal, Sebastien Collette, Shinji Imahori, Matias Korman, Stefan Langerman, Oded Schwartz, Shakhar Smorodinsky and Perouz Taslakian. Japan Conference on Computational Geometry and Graphs, 2009.

pdf file temporarily unavailable

Matching points with things , with Jean Cardinal, Sebastien Collette, Erik Demaine, Martin Demaine, Muriel Dulieu, Ruy Fabila-Monroy, Vi Hart, Ferran Hurtado, Stefan Langerman, Maria Saumell, Carlos Seara and Perouz Taslakian. Japan Conference on Computational Geometry and Graphs, 2009.

pdf file temporarily unavailable

Efficient Reconfiguration for Lattice-Based Modular Robots , with Nadia Benbernou, Mirela Damian, Erik Demaine, Robin Flatland, John Iacono and Stefanie Wuhrer. Proc. European Conference on Mobile Robotics, p.81-86, 2009.

pdf file ECMR.pdf

Realistic Reconfiguration of Crystalline (and Telecube) Robots , with Sebastien Collette, Mirela Damian, Erik Demaine, Dania El-Khechen, Robin Flatland, Stefan Langerman, Joseph O'Rourke, Val Pinciu, Suneeta Ramaswami, Vera Sacristan and Stefanie Wuhrer. In the Eighth International Workshop on the Algorithmic Foundations of Robotics (WAFR'08)

pdf file link

Decomposition of Multiple Coverings into More Parts , with Jean Cardinal, Sebastien Collette, Stefan Langerman, David Orden and Pedro Ramos. SODA'09

pdf file link

Reconfiguration of Cube-Style Modular Robots Using O(log n) Parallel Moves , with Sebastien Collette, Erik Demaine, Stefan Langerman, Vera Sacristan and Stefanie Wuhrer. ISAAC'08

pdf file link

Draining a Polygon -or- Rolling a Ball out of a Polygon , with Jean Cardinal, Sebastien Collette, Ferran Hurtado, Stefan Langerman and Joseph O'Rourke. CCCG 2008

pdf file link

Triangulating and Guarding Realistic Polygons , with Prosenjit Bose, Vida Dujmovic, Chris Gray, Stefan Langerman and Bettina Speckmann , CCCG 2008

pdf file link

Coloring Geometric Range Spaces , with Jean Cardinal, Sebastien Collette, Stefan Langerman and Shakhar Smorodinsky.
- 8th Latin American Theoretical Information Symposium. Buzios, Brazil. April 2008.
  - pdf file link
- 24th European Workshop on Computational Geometry. Nancy, France. March 2008.
  - pdf file see above
Vertex pops and popturns , with Brad Ballinger, Prosenjit Bose, Mirela Damian, Erik Demaine, Martin Demaine, Robin Flatland, Ferran Hurtado, Stefan Langerman, Joseph O'Rourke, Perouz Taslakian and Godfried Toussaint , 19th Canadian Conference on Computational Geometry Ottawa, Canada, August 2007

pdf file pops-cccg07.pdf

Linear Reconfiguration of Cube-Style Modular Robots , with Sebastien Collette, Mirela Damian, Erik Demaine, Robin Flatland, Stefan Langerman, Joseph O'Rourke, Suneeta Ramaswami, Vera Sacristan and Stefanie Wuhrer,
- XII Encuentros de Geometria Computacional (EGC 2007) Valladolid, Spain, June 2007.
  - pdf file cube-robots-EGC07.pdf
- 18th International Symposium on Algorithms and Computation (ISAAC) , Sendai, Japan, December 2007.
  - pdf file cbots_ISAAC.pdf
LUMINES Strategies , with Jean Cardinal, Sebastien Collette and Stefan Langerman , LNCS Proceedings of the 5th International Conference on Computers and Games (CG 2006) , Torino, Italy. vol. 4630, p.190-199, 2007.

pdf file lumines.pdf

Reconfiguring planar dihedral chains , with Henk Meijer. 22nd European Workshop on Computational Geometry (EWCG'06) , Delphi, Greece, March 27-29, 2006.

PDF file dihedral-ewcg06.pdf

Where to build a temple, and where to dig to find one , with Jean Cardinal, Sebastien Collette, John Iacono and Stefan Langerman. 22nd European Workshop on Computational Geometry (EWCG'06) , Delphi, Greece, March 27-29, 2006.

PDF file temples-ewcg06.pdf

Geometric Measures of Data Depth DIMACS Series in Discrete Mathematics and Theoretical Computer Science (vol.72 Data Depth: Robust Multivariate Analysis, Computational Geometry and Applications), R.Liu, R.Serfling, D.Souvaine eds, American Mathematical Society, (2006) pp.147-158.

pdf file depth.pdf

Reconfiguring Triangulations with Edge Flips and Point Moves with Prosenjit Bose and Pat Morin, 12th International Symposium on Graph Drawing (GD'04), City College, NYC. In Lecture Notes in Computer Science 3383, pages 1-11, 2004. * Invited for submission to Algorithmica (see journal version above)*

PostScript GD-triangulations.ps

PDF

GD-triangulations.pdf

or you can try

Springer official copy (permission may be required)

Unfolding Polyhedral Bands , with Erik Demaine, Stefan Langerman, Pat Morin, Joseph O'Rourke, Ileana Streinu and Godfried Toussaint, In proceedings of the 16th Canadian Conference on Computational Geometry (CCCG'04) , Concordia University, Montreal, August 9-11, 2004, pages 60-63. * Invited for submission to CGTA (see journal version above) *

PostScript file band-cccg.ps

Computing a Geometric Measure of the Similarity Between two Melodies , with Thomas Fevens, Stefan Langerman, Tomomi Matsui, Antonio Mesa, Yurai Nuñez, David Rappaport and Godfried Toussaint, in Proceedings of the 15th Canadian Conference on Computational Geometry (CCCG'03) , Dalhousie University, Halifax, August 11-13, 2003, pp. 81-84. * see full paper in journal section above *

PostScript file melody.ps

Computing Signed Permutations of Polygons, with Prosenjit Bose, Erik D. Demaine, Stefan Langerman, Henk Meijer, Mark Overmars and Godfried Toussaint, in Proceedings of the 14th Canadian Conference on Computational Geometry (CCCG'02), p.68-71 , University of Lethbridge, Alberta, Canada. August 12-14, 2002.

PostScript file (short version) 23m.ps (long version) 23l.ps

On Flat-State Connectivity of Chains with Fixed Acute Angles, with Erik D. Demaine, Henk Meijer, Joseph O'Rourke, Ileana Streinu and Godfried Toussaint, in Proceedings of the 14th Canadian Conference on Computational Geometry (CCCG'02), p.27-30 , University of Lethbridge, Alberta, Canada. August 12-14, 2002

PostScript file 16.ps

Flat-State Connectivity of Linkages Under Dihedral Motions, with Erik D. Demaine, Vida Dujmovic, Jeff Erickson, Stefan Langerman, Henk Meijer, Joseph O'Rourke, Mark Overmars, Michael Soss, Ileana Streinu and Godfried Toussaint, in Proceedings of the 13th Annual International Symposium on Algorithms and Computation (ISAAC 2002), Vancouver, B.C., Canada. November 2002: Lecture Notes in Computer Science, vol.2518, p.369-380.

PostScript file f2fISAAC.ps

Algorithms for Bivariate Medians and a Fermat-Torricelli Problem for Lines, with Stefan Langerman, Michael Soss and Godfried Toussaint, in Proceedings of the 13th Canadian Conference on Computational Geometry (CCCG'01) , University of Waterloo, August 13-15, 2001, pp. 21-24. * Invited for submission to CGTA (see journal version above)*

PostScript file ALST_CCCG.ps

Conference abstracts (no more than one page)

Geometric and combinatorial issues in data depth, at the Franco-Canadian Workshop on Combinatorial Algorithms (COMAL 2005) , McMaster University, Hamilton.

Technical Reports

On Computing the Bivariate Median and the Fermat-Torricelli Problem for Lines, with Michael Soss and Godfried Toussaint, Tech. Report # SOCS-01.2, School of Computer Science, McGill University, February, 2001.

PostScript file SOCS.01.2.ps compressed: SOCS.

Lower Bounds for Computing Statistical Depth, with Carmen Cortes, Francisco Gomez, Michael Soss and Godfried Toussaint, Tech. Report # SOCS-01.1, School of Computer Science, McGill University, February, 2001.

PostScript file SOCS.01.1.ps compressed: SOCS.

Conference talks

"Efficient reconfiguration of lattice-based modular robots" at ECMR'09.
"Reconfiguration of Cube-Style Modular Robots Using O(log n) Parallel Moves" at ISAAC'08, Gold Coast, Australia
"Realistic Reconfiguration of Crystalline (and Telecube) Robots" at WAFR'08, Guanajuato, Mexico.
"Triangulating and Guarding Realistic Polygons" at CCCG'08, Montreal, Canada
"Reconfiguring planar dihedral chains" at EWCG'06, Delphi, Greece
"Where to build a temple, and where to dig to find one" at EWCG'06, Delphi, Greece
"Geometric and combinatorial issues in data depth" at COMAL 2005, McMaster University, Hamilton. powerpoint slides
"Reconfiguring triangulations with edge flips and point moves" at Graph Drawing 2004, New York.
"Unfolding polyhedral bands" at CCCG 2004, Montreal.
"Computing a geometric measure of the similarity between two melodies" at CCCG 2003, Halifax.
"On the computation and robustness of some data depth notions". at DIMACS (2003), Rutgers University, New Brunswick, New Jersey.
"Computing signed permutations of polygons" at CCCG 2002, Lethbridge.
"Flat-state connectivity of linkages under dihedral motions" at ISAAC 2002, Vancouver.
"Algorithms for bivariate medians and a Fermat-Torricelli problem for lines" at CCCG 2001, Waterloo.

Some of the other talks I have given

Reconfiguring modular robots
- New York University - Brooklyn Polytechnic, July 2009.
- Carleton University, January 2009.
- University of Athens, November 2008.
Folding and unfolding polyhedra
- University of Athens, October 2007.
Computing a measure of polygonal chain similarity
- Universidad de la Habana, Cuba, April 2004 (3rd Cuban Workshop on Algorithms and Data Structures)
Recent results on stuck unknotted polygons.
- Universidad de la Habana, Cuba, April 2003 (2nd Cuban Workshop on Algorithms and Data Structures)
Bivariate medians.
- University of Ioannina, Greece, July 2001.

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