# Seminars & Events for 2011-2012

May 17, 2012
3:00pm - 4:00pm
##### An Introduction to Knot Homologies
###### Algebraic Topology Seminar

Knot homology theories associate to a knot or link a complex of graded modules whose graded Euler characteristic is a classical knot polynomial. This type of knot invariant has been increasingly influential in low-dimensional topology in the ten years or so since the first one was developed.

Speaker: Allison Gilmore, Princeton University
Location:
Fine Hall 214
May 18, 2012
2:00pm - 3:30pm
##### Perturbations of geodesic flows producing unbounded growth of energy
###### Ergodic Theory & Statistical Mechanics

We consider a geodesic flow on a manifold endowed with some generic Riemannian metric. We couple the geodesic flow with a time-dependent potential driven by an external dynamical system, which is assumed to satisfy some recurrence condition. We prove that there exist orbits whose energy grows unboundedly at a linear rate with respect to time; this growth rate is optimal.

Speaker: Marian Gidea , Institute for Advanced Study
Location:
Fine Hall 322
May 18, 2012
3:00pm - 4:00pm
##### On some fully non-linear PDEs and their applications in Kaehler geometry
###### Differential Geometry & Geometric Analysis Seminar

In this talk, we will discuss the so-called inverse $\sigma_k$ equation on Kahler manifolds. We will concentrate on examples of singular solutions and their application in Kahler geometry. Parts of the work are joint with Mijia Lai, Jian Song and Ben Weinkove.

Speaker: Hao Fang, University of Iowa
Location:
Fine Hall 314
September 21, 2012
2:30pm - 3:30pm
##### Deforming $G_2$ conifolds.
###### Differential Geometry & Geometric Analysis Seminar

A theorem of Dominic Joyce says that the moduli space of compact $G_2$ manifolds is smooth of dimension equal to the third Betti number of the manifold. We study the moduli space question for noncompact $G_2$ manifolds with one end, asymptotic to a metric cone of $G_2$ holonomy. This includes the explicit Bryant--Salamon manifolds as examples.

Speaker: Spiro Karigiannis, University of Waterloo
Location:
Fine Hall 314
October 16, 2014
2:00pm - 3:30pm
##### Moment estimates for square-free integers on short intervals
###### Ergodic Theory & Statistical Mechanics

Square-free integers are known to have asymptotic density 6/(pi^2). Fix some x and let n be distributed uniformly on the integers between 1 and x. Consider the corresponding variance of the number of square-free integers on a short interval [n+1, n+N] and let x tend to infinity.

Speaker: Maria Avdeeva, Princeton University
Location:
Fine Hall 601