The Lehigh/Lafayette Geometry and Topology Seminar

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Spring Semester 2008

 

 

Spring’s talks are organized into a mini-conference which will meet on Saturday, March 29, 2008

 

All talks will be on the second floor of Pardee Hall at Lafayette College.  Directions to Lafayette College can be found here, and a campus map can be found here.  Visitors can either park in front of Pardee Hall and enter through the door facing the quad or can park at the Markle Deck.  From Markle Deck, cross High street and head towards the quad (the library, the building with a lot of glass, should be on your right).  Cross the quad; Pardee will be in front of you and slightly to the left.  Enter through the door facing the quad.

 

 

Schedule of Events

 

 

9:30 – 10:00

 

Coffee and snacks

 

 

10:00 – 10:50

Adrian Butscher
(Stanford University)

 

Title: Gluing constructions of CMC surfaces in general Riemannian manifolds

 

Abstract: I will review the now classical Kapouleas gluing construction for CMC surfaces in Euclidean space and present some results and work in progress concerning the extensions of this theory to general ambient manifolds. An important feature which emerges is that the ambient Riemannian curvature seems to play a significant role in the existence of such surfaces; and exploiting this, it seems possible to construct examples of CMC surfaces having properties very different from their Euclidean analogues.

11:00 – 11:50

Ross Geoghegan
(SUNY at Binghamton)

 

Title: New results about Thompson's groups

 

Abstract:  This talk is about the Thompson groups T and F; T is the group of all PL dyadic homeomorphisms of the circle, and F is the subgroup which fixes some base point. Both are finitely presented groups of type FP∞. I will discuss two new results.

The first result (joint work with Bieri and Kochloukova) is a complete description of the Bieri-Neumann-Strebel-Renz invariants for F.

The second result (joint work with Marco Varisco) is our proof that the Whitehead group of T is non-trivial. As far as I know, this is the first known non-trivial K-theory of a Thompson group. It is an application of general work of Lueck-Reich-Rognes-Varisco. We also get  other K-theoric information about T.

 

12:00 – 1: 00

 

Lunch (provided)

 

 

1:10 – 2:00

 

Tara Holm

(Cornell University)

 

 

 

Title: Symplectic techniques for computing invariants of orbifolds

 

Abstract:  We present techniques for computing the various cohomology rings associated to an orbifold X that arises as a symplectic quotient M//G. The first result along these lines is due to Kirwan; it relates the cohomology of the quotient M//G to the equivariant cohomology of M. This technique can be generalized, when M//G is an orbifold, to compute the so-called stringy invariants of the orbifold. We will demonstrate these results through several detailed examples, and will conclude with a brief discussion of coefficient rings. This talk is based on joint projects with Goldin and Knutson; Goldin, Harada and Kimura; Sjamaar; and Tolman. No symplectic background will be assumed.

 

2:10 – 3:00

Tim Riley
(Bristol University)

 

Title: Hydra Groups

Abstract: I will describe a new family of groups exhibiting wild geometric and computational features in the context of their Conjugacy Problems.  These features stem from manifestations of "Hercules versus the hydra battles."  This is joint work with Martin Bridson.

 

 

 

 

Past seminar schedules:

 

2006-2007 Academic Year

2005-2006 Academic Year

2004-2005 Academic Year

2003-2004 Academic Year

2002-2003 Academic Year

 

For further information, contact Ethan Berkove at berkovee at lafayette dot edu.

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