Seminars and Colloquia by Series

Wednesday, February 22, 2017 - 14:05 , Location: Skiles 006 , Andrew McCullough , Georgia Tech , Organizer: Justin Lanier
We will discuss a way of explicitly constructing ribbon knots using one-two handle canceling pairs.  We will also mention how this is related to some recent work of Yasui, namely that there are infinitely many knots in (S^3, std) with negative maximal Thurston-Bennequin invariant for which Legendrian surgery yields a reducible manifold.
Wednesday, February 15, 2017 - 14:05 , Location: Skiles 006 , Surena Hozoori , Georgia Tech , Organizer: Justin Lanier
In this talk, I will define Conley-Zehnder index of a periodic Reeb orbit and will give several characterizations of this invariant. Conley-Zehnder index plays an important role in computing the dimension of certain families of J-holomorphic curves in the symplectization of a contact manifold.
Wednesday, February 8, 2017 - 14:05 , Location: Skiles 006 , Caitlin Leverson , Georgia Tech , Organizer: Justin Lanier
Normal rulings are decompositions of a projection of a Legendrian knot or link. Not every link has a normal ruling, so existence of a normal ruling gives a Legendrian link invariant. However, one can use the normal rulings of a link to define the ruling polynomial of a link, which is a more useful Legendrian knot invariant. In this talk, we will discuss normal rulings of Legendrian links in various manifolds and prove that the ruling polynomial is a Legendrian link invariant.
Wednesday, February 1, 2017 - 14:05 , Location: Skiles 006 , Justin Lanier , Georgia Tech , Organizer: Justin Lanier
Wajnryb showed that the mapping class group of a surface can be generated by two elements, each given as a product of Dehn twists. We will discuss a follow-up paper by Korkmaz, "Generating the surface mapping class group by two elements." Korkmaz shows that one of the generators may be taken to be a single Dehn twist instead. He then uses his construction to further prove the striking fact that the two generators can be taken to be periodic elements, each of order 4g+2, where g is the genus of the surface.
Wednesday, November 30, 2016 - 14:00 , Location: Skiles 006 , Dr , Ediburgh , Organizer: Thang Le
Wednesday, November 23, 2016 - 14:00 , Location: None , None , None , Organizer: John Etnyre
Wednesday, November 16, 2016 - 14:05 , Location: Skiles 006 , Caitlin Leverson , Georgia Tech , Organizer: Shane Scott
We will review the definition of the Chekanov-Eliashberg differentialgraded algebra for Legendrian knots in R^3 and look at examples tounderstand a few of the invariants that come from Legendrian contacthomology.
Wednesday, November 9, 2016 - 14:05 , Location: Skiles 006 , Caitlin Leverson , Georgia Tech , Organizer: Shane Scott
We will review the definition of the Chekanov-Eliashberg differentialgraded algebra for Legendrian knots in R^3 and look at examples tounderstand a few of the invariants that come from Legendrian contacthomology.
Wednesday, November 2, 2016 - 14:05 , Location: Skiles 006 , Sudipta Kolay , Georgia Tech , Organizer: Sudipta Kolay
We will show that every closed orientable 3-manifold bounds an orientable 4-manifold. If time permits, we will also see an application to embedding closed orientable 3-manifolds to R^5.
Wednesday, October 19, 2016 - 14:00 , Location: Skiles 006 , Andrew McCullough , Georgia Institute of Technology , andrew.mccullough@gatech.edu , Organizer: Andrew McCullough
We will discuss some facts about intersection forms on closed, oriented 4-manifolds.  We will also sketch the proof that for two closed, oriented, simply connected manifolds, they are homotopy equivalent if and only if they have isomorphic intersection forms. 

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