The organizers were
Past Seminar Schedules and Abstracts:
Schedule, Fall 2008
See also the CUNY Geometry and Topology Seminar.
Tuesday December 9 (1:30-3:00 pm): Reading Seminar
Friday August 15: CUNY Isoperimetric Inequalities Workshop
Speakers: M. Lucia, G. LaNave, M. Ludwig
Tuesday September 16 (3-4 pm): Kei Kondo (Tokai University)
Total curvatures of model surfaces control topology of complete open
manifolds with radial curvature bounded below
Cohn-Vossen is one of pioneers in global differential geometry. About 70 years ago, he investigated the relationship between the total curvature and the
of complete open surfaces. Some of his results were generalized to any
dimensional manifolds :
The splitting theorem ([Toponogov, 1959], [Cheeger--Gromoll, 1971]), The
classic structure theorems
for complete open Riemannian manifolds ([Gromoll--Meyer, 1969],
Note that all these results above are assumed to have non-negative
Here we want to generalize some results of complete open surfaces to
from radial curvature geometry's standpoint, where the curvature may change signs wildly. In this talk, I would like to talk about the relationship between total
curvatures and Busemann functions
due to K. Shiohama and our results from recent collaborative works with
Professor Minoru Tanaka.
Tuesday September 23: Jason Behrstock (Lehman College, CUNY)
"Geometry and Rigidity of Mapping Class Groups"
Abstract: In this talk accessible to the general geometry/topology
audience, we will discuss the geometry of the mapping class group
and applications to quasi-isometric rigidity. This will include the recent
result that any quasi-isometry of the mapping class group is a bounded
distance away from any isometry induced by left multiplication. This has the
consequence that any finitely generated group which is quasi-isometric
to the mapping class groups is, up to a finite group, isomorphic to it.
This talk will cover all relevant definitions and survey the relevant history
as well as joint work with B. Kleiner, Y. Minsky, and L. Mosher.
Tuesday September 30: No meeting
Tuesday October 7: Michael Puls (John Jay, CUNY)
"The first reduced lp-
cohomology of finitely generated infinite
Abstract: We will define the first reduced lp-
cohomology space of a
finitely generated infinite group, where p is a real number
one. We will then give some results concerning the vanishing and
non-vanishing of this space. We will also give links between the first
reduced lp-cohomology space of a group with the p-harmonic
functions on the group and various boundaries of the group. This will
be an expository talk.
Tuesday October 14: no meeting
CUNY on a Monday Schedule
Tuesday October 21: no meeting
Conflict with committee meetings
Friday October 24 (11:00 am -12:00 pm): Reading Seminar
Michael Munn (City Tech, CUNY) presenting
Tuesday October 28: Dan Lee (Queens College, CUNY)
Title: The Riemannian Penrose Inequality in dimensions less than 8.
Abstract: The Riemannian Penrose Inequality was first proved in three
dimensions in 1997 by G. Huisken and T. Ilmanen for the case
of a single black hole. In 1999, H. Bray extended this result to the
general case of multiple black holes using a different
technique. I will discuss joint work with H. Bray on extending Bray's
technique to dimensions less than 8.
Tuesday November 4 (1:30-3:00 pm): Reading Seminar (Election Day)
Title: Mass Transport II
Michael Munn (City Tech, CUNY) presenting
Tuesday November 11: no meeting
Tuesday November 18 (1:30-3:00 pm, 4419): Reading Seminar
Isoperimetric Inequalities and Mass Transport: Introduction
Isaac Chavel presenting
Friday November 21 (11-12:00 Room 3309): Steve Ferry (Rutgers)
Title: "Gromov-Hausdorff convergence to non-manifolds"
Abstract: We will discuss families of Riemannian manifolds with a common contractibility function that converge in
Gromov-Hausdorff space to non-manifolds. It turns out that these limits have many properties of manifolds, including
(at least) simple-homotopy types and rational characteristic classes.
Friday December 5: Two seminars
- (11-12:00 Room 3309): Bianca Santoro (Duke)
Title: "Complete Ricci flat Kahler manifolds with topology at infinity"
Abstract: In this talk, we plan to explain some existence results for
complete Ricci-flat \kahler metrics on special types of manifolds with
prescribed behavior at infinity. This result provides an interesting
corollary: we are able to construct new examples of Kahler Ricci-flat
metrics with richer asymptotic topology.
(2-3:00 Room 3309): Fernando Marquez (IMPA)
Title: The space of positive scalar curvature metrics on the three sphere
Abstract: We will discuss a proof of the path connectedness of
the space of positive scalar curvature metrics on the three sphere.
The proof uses Ricci flow with surgery and the connected sum construction
of Gromov and Lawson. The work of Perelman on Hamilton's Ricci flow is
Isaac Chavel presents
isoperimetric inequalities and mass transport
Tuesday December 16: no meeting
Tuesday December 23 (1:30-3:00 pm): Reading Seminar