Seminars and Colloquia by Series
Monday, May 8, 2017 - 14:00 , Location: Skiles 006 , Tye Lidman , NCSU , Organizer: Jennifer Hom
We will discuss a relation between some notions in three-dimensional topology and four-dimensional aspects of knot theory.
Monday, April 24, 2017 - 14:30 , Location: UGA Room 303 , Alexandru Oancea and Basak Gurel , Jussieu and University of Central Florida , Organizer: Caitlin Leverson
Alexandru Oancea: Title: Symplectic homology for cobordisms Abstract: Symplectic homology for a Liouville cobordism - possibly filled at the negative end - generalizes simultaneously the symplectic homology of Liouville domains and the Rabinowitz-Floer homology of their boundaries. I will explain its definition, some of its properties, and give a sample application which shows how it can be used in order to obstruct cobordisms between contact manifolds. Based on joint work with Kai Cieliebak and Peter Albers. Basak Gürel: Title: From Lusternik-Schnirelmann theory to Conley conjecture Abstract: In this talk I will discuss a recent result showing that whenever a closed symplectic manifold admits a Hamiltonian diffeomorphism with finitely many simple periodic orbits, the manifold has a spherical homology class of degree two with positive symplectic area and positive integral of the first Chern class. This theorem encompasses all known cases of the Conley conjecture (symplectic CY and negative monotone manifolds) and also some new ones (e.g., weakly exact symplectic manifolds with non-vanishing first Chern class). The proof hinges on a general Lusternik–Schnirelmann type result that, under some natural additional conditions, the sequence of mean spectral invariants for the iterations of a Hamiltonian diffeomorphism never stabilizes. Based on joint work with Viktor Ginzburg.
Monday, April 17, 2017 - 14:05 , Location: Skiles 006 , Chaohui Zhang , Morehouse College , Organizer: Dan Margalit
Let S be a Riemann surface of type (p,1), p > 1. Let f be a point-pushing pseudo-Anosov map of S. Let t(f) denote the translation length of f on the curve complex for S. According to Masur-Minsky, t(f) has a uniform positive lower bound c_p that only depends on the genus p.Let F be the subgroup of the mapping class group of S consisting of point-pushing mapping classes. Denote by L(F) the infimum of t(f) for f in F pseudo-Anosov. We know that L(F) is it least c_p. In this talk we improve this result by establishing the inequalities .8 <= L(F) <= 1 for every genus p > 1.
Friday, April 14, 2017 - 14:00 , Location: Skiles 006 , Henry Segerman , Oklahoma State University , Organizer: John Etnyre
This is joint work with Hyam Rubinstein. Matveev and Piergallini independently show that the set of triangulations of a three-manifold is connected under 2-3 and 3-2 Pachner moves, excepting triangulations with only one tetrahedron. We give a more direct proof of their result which (in work in progress) allows us to extend the result to triangulations of four-manifolds.