Courant Institute of Mathematical Sciences
New York University

Geometry Seminar

This seminar covers a wide range of topics in geometry with particular emphasis on discrete geometry, computational geometry and algorithmic real algebraic geometry. Many of the speakers are Courant Institute visitors and postdocs. A seminar talk may cover original research or report on an interesting paper. The seminar is run by Janos Pach and Richard Pollack

For time & location, click on any semester below.

Spring 2012.

Fall 2011.

Fall 2010.

Spring 2010.

Fall 2009.

Spring 2009.

Fall 2008.

Spring 2008

February 5, 2008, Jacob Fox, Princeton University: Density theorems for bipartite graphs and related Ramsey-type results

February 12, 2008, Ileana Streinu, Smith College, Northampton: Slider pinning and combinatorial planar rigidity

February 26, 2008, Mikhail Gromov, NYU and IHES: From combinatorics to topology: Back and forth

March 11, 2008, Thierry Zell, Vassar College: Topological complexity of transcendental sets

March 18, 2008, Saugata Basu, Georgia Tech.: Combinatorial complexity in o-minimal geometry

April 1, 2008, Martin Charles Golumbic, Haifa University: Twenty years of EPT graphs: Edge intersection graphs of paths in a tree

April 8, 2008, Joe Mitchell, Stony Brook University: Approximation algorithms for relay placement in the plane

April 15, 2008, Noga Alon, Tel Aviv University and IAS: Nearly diagonally dominant matrices and their applications

April 29, 2008, Edward Swartz, Cornell University: Face enumeration on manifolds

May 6, 2008, Doron Puder, Jerusalem and New York: Word maps and spectra of random graph lifts

May 13, 2008, Gabor Tardos, Simon Fraser University, Vancouver: Coloring points and rectangles

Fall 2007

September 11, 2007, Andreas Holmsen, University of Bergen, Norway: Points surrounding the origin

September 25, 2007, Mike Develin, American Inst. Mathematics and Columbia University: Tropical oriented matroids

October 2, 2007, Gil Kalai, Hebrew University, Jerusalem and Yale University, New Haven: F-vectors: Some recent developments

October 9, 2007, Sue Whitesides, McGill University, Montreal: Fixed parameter tractability in geometry and graph drawing

October 16, 2007, Tom Zaslavsky, Binghamton University: Totally frustrated states: A physics-like generalization of graph coloring

October 30, 2007, Alain Pajor, Universite de Marne-la-Vallee: Some geometry of random 0-1 polytopes

November 6, 2007, One-Day Combinatorial Geometry Conference: 10:30-11:00am Andrew H. Suk, Courant Institute, NYU; K-cross-free hypergraphs (in rm. 1314); 11:00am-11:30am Alfredo Hubard, Courant Institute, NYU; A Ham-Sandwich type theorem (in rm. 1314); 11:30am-12:00pm Problem Session (in rm. 1314); 3:45-4:15pm Padmini Mukkamala, Rutgers University, New Brunswick; Drawing connected cubic graphs with four slopes (in rm. 402); 4:15-4:45pm Ricky Pollack, CIMS, New York; Double permutation sequences (in rm. 402); 5:00-5:30pm Andreas Holmsen, Bergen, New York; Intersecting convex sets by rays (in rm. 402); 6:00-7:00pm Rom Pinchasi, Technion, Haifa; Topological hypergraphs (in rm. 613)

November 13, 2007, Bill Steiger, Rutgers University: Some combinatorial and algorithmic applications of the Borsuk-Ulam theorem

November 20, 2007, Gaiane Panina, St. Petersburg, Russia: A.D. Alexandrov's conjecture and hyperbolic virtual polytopes

Spring 2007

February 13, 2007, Esther Ezra, Tel Aviv University: Translational motion planning in 3-space

February 20, 2007, Boris Bukh, Princeton University: Measurable chromatic number and sets with excluded distances

February 27, 2007, LECTURE CANCELLED!!! Micha Sharir, Tel Aviv University and NYU.: Weak epsilon-nets in convex position: (inverse) Ackermann strikes again

March 6, 2007, Assaf Naor, NYU: L_1 embeddings of the transportation cost metric on planar grids

March 20, 2007, J. Maurice Rojas, Texas A&M University: The complete fewnomial conjecture

March 27, 2007, Joe Mitchell, Stony Brook University: Improved approximation algorithms for TSP with neighborhoods

April 17, 2007, David Larman, University College London: Skeleta of convex bodies

April 24, 2007, Marjorie Senechal, Smith College, Northampton: A point set puzzle revisited

May 8, 2007, David Kirkpatrick, University of British Columbia, Vancouver: Bit-thrifty evaluation of geometric predicates

Fall 2006

September 19, 2006 Jacob Fox, Princeton University: Ramsey-type results for intersection graphs of geometric objects

September 26, 2006 Geza Toth, Renyi Institute, Hungarian Academy: Crossing numbers of toroidal graphs

October 3, 2006 Thomas Zaslavsky, Binghamton University: Arrangements of topological hyperplanes

October 10, 2006 Csaba D. Toth, M.I.T.: Distinct triangle areas in the plane and in three-space

October 17, 2006 Xiaomin Chen, Google: Delauney graphs and conflict-free colorings

November 14, 2006 Gil Kalai, Yale University and Hebrew University: Neighborly embedded manifolds and continuous hashing

November 21, 2006 Tetsuo Asano, JAIST, Kanazawa, Japan: Linear-space implementation of multi-dimensional scaling with applications

November 28, 2006 Nir Halman, M.I.T.: The convex dimension of a graph

December 19, 2006 Adrian Dumitrescu, University of Wisconsin, Milwaukee: On triangles of minimum area and tetrahedra of minimum volume

Spring 2006

January 10, 2006 Jacob Fox, M. I. T., Cambridge: On the decay of crossing numbers

February 21, 2006 Micha Sharir, Tel Aviv University and Courant Institute: Random triangulations of a planar point set

February 21, 2006 Tudor Zamfirescu, Universitat Dortmund: Diameters and antipodes

February 28, 2006 Thomas Zaslavsky, Binghamton University: Inside-out polytopes

March 14, 2006 Nancy Amato, Texas A&M University: Using motion planning to study molecular motions

March 21, 2006 Andreas Holmsen, Bergen and New York: Lines intersecting pairwise disjoint congruent spheres in d-space

March 28, 2006 Tibor Szabo, ETH Zurich: Making or avoiding a planar graph

April 11, 2006 Kira Adaricheva, Harold Washington College, Chicago: Convex geometries and Jamison's problem

May 9, 2006 Rolf Schneider, Universitat Freiburg: Random polytopes and isoperimetric inequalities

Fall 2005

September 6, 2005 Micha Sharir, Tel Aviv University and NYU: Maintaining a triangulation of moving points

September 20, 2005 Joe Mitchell, Stony Brook University: Sticks, french fries and potatoes in polygons

September 27, 2005 Shakhar Smorodinsky, Courant Institute, NYU: On the chromatic number of some geometric hypergraphs

October 11, 2005 Gil Kalai, Yale University and Hebrew University: Helly type theorems, their topological analogs, and Leray complexes

October 18, 2005 Igor Pak, M. I. T., Cambridge

The geometry of convex polyhedra

October 25, 2005 Leonid Gurvits, Los Alamos National Laboratory

Hyperbolic van der Waerden and Valiant-Schrijver conjectures

November 1, 2005 Eyal Ackerman, Technion, Israel Institute of Technology: The maximum number of edges in k-quasi-planar graphs

November 29, 2005 Nir Halman, Massachusetts Institute of Technology: Discrete Helly-type theorems
Special place: CUNY Graduate Center 365 Fifth Ave., 4th floor math. lounge!

Spring 2005

February 1, 2005 Gil Kalai, Yale University and Hebrew University: Discrete isoperimetry and Fourier analysis of Boolean functions

February 8, 2005 Micha Sharir, Courant Institute and Tel Aviv University: Counting crossing-free configurations in the plane

February 22, 2005 Jeff Erickson, University of Illinois at Urbana-Champaign: Greedy optimal homotopy and homology generators

March 1, 2005 Geza Toth Renyi Institute, Budapest: Decomposition of multiple coverings

March 8, 2005 Igor Pak M.I.T., Cambridge: Convex polytopes, rigidity, and classical geometry

March 22, 2005 Adrian Dumitrescu University of Wisconsin, Milwaukee: On distinct distances from a vertex of a convex polygon

March 29, 2005 Noga Alon I.A.S. and Tel Aviv University: Boxes and voting paradoxes

April 19, 2005 Ken Clarkson Bell Laboratories: Improved approximation algorithms for geometric set cover

April 26, 2005 Rom Pinchasi Technion, Haifa: On geometric graphs with no pair of parallel edges

May 3, 2005 Gabor Tardos Renyi Institute, Budapest: On the complexity of pseudo-circle arrangements

May 10, 2005 Marjorie Senechal Smith College, Northampton: Tiling 3-space with golden rhombohedra

Fall 2004

September 21, 2004 Bill Steiger, Rutgers University: Convex hull of random hyperplanes in R^3

September 29 - October 2, 2004 GD 2004 at City College, CUNY: 12th International Symposium on Graph Drawing

October 5, 2004 Thorsten Theobald, Yale University: Radii minimal projections of polytopes and constrained optimization of symmetric polynomials

October 12, 2004 Frank Morgan, Williams College: Planar soap bubble clusters

October 19, 2004 Hervé Brönnimann, Polytechnic University, Brooklyn: Tangents to (various kinds) of objects in R^3

October 26, 2004 Mike Develin, American Institute of Mathematics: A new proof of Stanley's reciprocity theorem

November 2, 2004 Joshua Cooper, Courant Institute, NYU: Erdos-Hajnal sets and semigroup decompositions

November 9, 2004 Dmitry Novikov, Cornell University, Ithaca: Convex-concave subsets of real projective space

November 16, 2004 Tetsuo Asano, Japan Advanced Institute of Science and Technology: Polyline fitting of planar points under min-sum criteria

November 30, 2004 Jacob E. Goodman, City College, CUNY: Double-permutation sequences and pseudoline transversals

Spring 2004

January 27, 2004 Shakhar Smorodinsky, Tel Aviv University and MSRI: On conflict-free colorings

February 3, 2004 Andrei Raigorodski, Moscow State University: On the chromatic numbers of some spaces

February 17, 2004 Henry Cohn, Microsoft Research: Optimality of the Leech lattice among lattices

March 2, 2004 Ileana Streinu, Smith College: Pseudo-lines, pseudo-triangles and other pseudos

March 9, 2004 Joe Mitchell, SUNY Stony Brook: Computing the Visibility Graph of Points Within a Polygon

March 23, 2004 Carly Klivans, Cornell University: Obstructions to Shiftedness

March 30, 2004 Oleg Musin, Moscow State Universty: The Kissing Number in Four Dimensions

May 11, 2004 Louis J. Billera, Cornell University: Geometric Enumeration, Quasisymmetric Functions and a Construction of Provan

May 18, 2004 Andreas Holmsen, University of Bergen: Transversals and permutations of planar families of translates

May 18, 2004 Van Vu, University of California San Diego: Nearly sharp bounds for Erd\H{o}s distinct distances in high dimensions

Spring 2003

February 11, 2003 Micha Sharir, Tel Aviv University and NYU: Cutting triangular cycles of lines in space

March 4, 2003 Jozsef Solymosi, UC San Diego: On a problem of Erdos and Szemeredi

March 11, 2003 Karoly Bezdek, Eotvos University, Budapest and Cornell University, Ithaca: The Kneser-Poulsen conjecture for spherical polytopes

March 18, 2003 Rados Radoicic, M.I.T., Cambridge: On a coloring problem for the integer grid

March 25, 2003 Geza Toth, Renyi Institute, Budapest: Relaxing planarity for topological graphs

April 1, 2003 Valeriu Soltan, George Mason University: Affine diameters of convex bodies

April 8, 2003 Joseph Malkevitch, York College, CUNY: Insights about plane graphs from Euler relations

Fall 2002

September 24, 2002 Christian Haase, Duke University: Lattice polygons and the number 2 i + 7

October 8, 2002 Geza Toth, Renyi Institute, Budapest: Monotone drawings of planar graphs

October 15, 2002 Ileana Streinu, Smith College: On the number of embeddings of minimally rigid graphs

October 22, 2002 Sinai Robins, Temple University: Solid angles of polytopes

November 5, 2002 Andreas Holmsen, University of Bergen: A Helly-type theorem for line transversals to disjoint unit balls

November 12, 2002 Gabor Tardos, Renyi Institute, Budapest: Distinct distances in higher dimensions

November 19, 2002 Bill Steiger, Rutgers University, New Brunswick: Long monotone paths in line arrangements

December 3, 2002 Mike Develin, University of California, Berkeley: LP-orientations of cubes and crosspolytopes

December 10, 2002 Avi Wigderson, IAS, Princeton and Hebrew University: Expander graphs -- where combinatorics and algebra compete and cooperate

Spring 2002

February 12, 2002 Adrian Dumitrescu, University of Wisconsin: Issues in motion planning of metamorphic systems

February 19, 2002 Konstantin Rybnikov, Cornell University: Maxwell's correspondence and gain graphs

February 26, 2002 Micha Sharir, Tel Aviv University and NYU: Lower envelopes and their overlays

March 5, 2002 Rados Radoicic, M. I. T.: Noncrossing configurations in geometric graphs

March 12, 2002 Zoltan Furedi, University of Illinois, Urbana: Covering a triangle with homothetic copies

March 19, 2002 Rom Pinchasi, M. I. T.: Extremal problems in graph drawings in the plane

March 26, 2002 Yunhong Zhou, Compaq Systems Research Center, Palo Alto: Geometric permutations of disjoint unit balls

April 2, 2002 Shmuel Onn, Technion, Haifa: Hilbert polytopes and universal Grobner bases

April 9, 2002 Gyula O. H. Katona, Renyi Institute, Hungarian Academy of Sciences: A coding problem for pairs of sets

April 23, 2002 Richard Pollack, Courant Institute, NYU: On the Betti-numbers of semi-algebraic sets

April 30, 2002 R. Daniel Mauldin, University of North Texas, Denton: The solution of Steinhaus' lattice point problem

Fall 2001

October 2, 2001 Frank Harary, New Mexico State University: Combinatorial games on graphs, meshes and chess boards: Unsolved Problems

October 9, 2001 Micha Sharir, Tel Aviv University: Incidences and related problems

October 16, 2001 Bob Connelly, Cornell University: The Kneser-Poulsen conjecture in the plane

October 23, 2001 Vladlen Koltun, Tel Aviv University: Recent Developments Concerning Vertical Decompositions

October 30, 2001 Boris Aronov, Polytechnic University: Many Faces in Arrangements of Pseudo-Segments and Circles

November 13, 2001 Maria Chudnovsky, Institute for Advanced Study: Triangulated spheres and colored cliques

November 20, 2001 Ileana Streinu, Smith College: Expansive motions and the polytope of pointed eseudo-triangulations

December 4, 2001 Cliff Smyth, Institute for Advanced Study: Equilateral or 1-distance sets and Kusner's conjecture