Hyperbolic Geometry Seminar

Location

Starting in Spring 2023  the seminar will go back to in-person talks. We will also attempt to run the seminar as  hybrid using zoom.   Zoom doors will open a few  minutes before the seminar for chatter and self provided coffee, tea, beer, wine, cocktail, aperitif,  digestif, cheese, and snacks depending on your time zone and predilection.   If you would like to be put on the email list contact Ara Basmajian (abasmajian@gc.cuny.edu). The zoom link for the upcoming seminar will be included in the weekly mailing to the email list. 

Due to the travel schedules of the three organizers,  we will run a shorter seminar series than usual this semester. The seminar will run from 

Febrary 24 to March 31, 2026.

Time

Tuesdays 2:45pm–3:45pm, room 5417.  

February 24: John Hubbard (Cornell U.)

Title: Mating  polynomials and Fuchsian groups

Abstract:  Under appropriate circumstances, we can "mate" two polynomials by putting the planes on which the polynomials act as the upper hemisphere and the lower hemisphere of a sphere and collapsing their external rays, to produce a rational function.

Under appropriate circumstances we an put the half-planes on which Fuchsian groups act as the upper half-plane and the lower half-plane of the Riemann sphere, and collapse in each the leaves of a lamination, to produce a Kleinian group which is the fundamental group of a hyperbolic 3-manifold that fibers over the circle.

These two constructions are obviously parallel, two entries of the Sullivan dictionary, and both give rise to "exotic" topology: Peano curves and the like.  It is a bit like marking a piece of string, winding it up into a ball, and having the markings turn into a design on the ball.

March 10: Dragomir Saric (CUNY)

Title:

Abstract:

March 24: No seminar (SLMath workshop)