Max Dehn Seminar

on Geometry, Topology, Dynamics, and Groups

Fall 2017 Wednesday 3:15 - 4:15, Room LCB 225

Date Speaker Title click for abstract (if available)
August 30
Moon Duchin
Tufts University
Discrete curvature, with applications
September 20
Florian Richter
The Ohio State University
October 18
Marco Lopez
University of North Texas
Dimension of shrinking target sets arising from non-autonomous dynamics.
In analogy to the set of well-approximable numbers in Diophantine approximation, a shrinking target set is defined as the set of points in a metric space, X, whose orbits under a dynamical system on X hit infinitely often a ball of radius shrinking to zero. Using techniques from thermodynamic formalism we establish a formula for the Hausdorff dimension of such sets in the context of non-autonomous iterated function systems.
October 25
Sang-hyun Kim
Seoul National University
Free products in Diff(S1)
We prove that if G is a finitely generated non-virtually-abelian group, then (G X Z) * Z does not embed into Diff^2(S^1). In particular, the class of subgroups of Diff^r(S^1) is not closed under taking free products for each r >= 2. We complete the classification of RAAGs embeddable in Diff^r(S^1) for each integer r, answering a question in a paper of M. Kapovich. (Joint work with Thomas Koberda)

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Max Dehn Seminar is organized by Mladen Bestvina, Ken Bromberg, Jon Chaika,
Donald Robertson, Domingo Toledo, and Kevin Wortman.

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