Max Dehn Seminar
on Geometry, Topology, Dynamics, and Groups
Academic year 2008  2009
Date  Speaker  Title — click for abstract (if available) 
January 23, 2008 
Christopher Cashen University of Utah 
Quasiisometries between tubular groups 
January 30, 2008 
Christopher Cashen University of Utah 
Quasiisometries between tubular groups, II 
February 6, 2008 
Dariusz Wilcznski Utah State University 
Composition Algebras and the Fundamental Theorem of Algebra for Polynomial Equations with a Tame Tail 
February 13, 2008 
Mladen Bestvina University of Utah 
Can higher rank lattices embed in Out(F_n)? 
February 27, 2008 
Benson Farb University of Chicago 
Analogies and contrasts between Riemann's moduli space and locally symmetric spaces 
March 5, 2008 
Yves de Cornulier University of Rennes 
Lie groups, their Dehn functions, and their asymptotic cones 
April 2, 2008 
Kevin Wortman University of Utah 
Cohomology of rank one arithmetic groups over function fields 
April 10, 2008 
Alexander Fel'shtyn Boise State University 
Groups with proerty R_{∞} and twisted BurnsideFrobenius theorem 
April 16, 2008 
Daniel Allcock University of Texas at Austin 
The Hurwitz monodromy problem in degree 4 
September 17, 2008 
Mladen Bestvina University of Utah 
A hyperbolic Out(F_n)complex, Part I 
September 24, 2008 
Mladen Bestvina University of Utah 
A New Proof of Morita's Theorem 
October 3, 2008 
JeanFrancois Lafont The Ohio State University 
A introduction to algebraic Ktheory 
October 8, 2008 
Yael Algom Kfir University of Utah 
Negative curvature phenomena in outer space 
October 22, 2008 
Mladen Bestvina University of Utah 
A hyperbolic Out(F_n)complex, Part II 
November 12, 2008 
Ken Bromberg University of Utah 
Convexity of length functions on FenchelNielsen coordinates for Teichmüller space 
November 29, 2008 
Ian Biringer University of Chicago 
Geometry and rank of closed hyperbolic 3manifolds 
December 3, 2008 
Julien Paupert University of Utah 
Discrete complex reflection groups in PU(2,1) 
January 21, 2009 
Kevin Wortman University of Utah 
Dehn functions of linear groups 
January 28, 2009 
Kevin Wortman University of Utah 
Dehn functions of linear groups II 
February 4, 2009 
KaiUwe Bux University of Virginia 
Thompson's group V is linear (or at least, it should be)
V has subgroups that are so close to being a BNpair
that the classical proof for simplicity of linear groups with
irreducible Coxeter system goes through almost without change.
It turns out that the subgroup F plays the role of the solvable
Borel subgroup. [joint work with Jim Belk]

March 27, 2009 
Martin Bridgeman Boston College 
Orthospectra of GEodesic Laminations
Given a measured lamination on a finite area hyperbolic surface we
consider a natural measure M on the real line obtained by taking the
pushforward of the volume measure of the unit tangent bundle of the surface
under an intersection function associated with the lamination. We show that
the measure M gives summation identities for the Rogers dilogarithm function
on the moduli space of a surface.

April 9, 2009 
Robert Young IHES 
The Dehn function of SL(n,Z)
The Dehn function is a group invariant which connects geometric and
combinatorial group theory; it measures both the difficulty of the
word problem and the area necessary to fill a closed curve in an
associated space with a disc. The behavior of the Dehn function for
highrank lattices in highrank symmetric spaces has long been an open
question; one particularly interesting case is SL(n,Z). Thurston
conjectured that SL(n,Z) has a quadratic Dehn function when n>=4.
This differs from the behavior for n=2 (when the Dehn function is
linear) and for n=3 (when it is exponential). In this talk, I will
discuss some of the background of the problem and sketch a proof that
the Dehn function of SL(n,Z) is at most quartic when n >= 5.

April 22, 2009 
Natasa Macura University of Utah/ Trinity University 
— 
April 30, 2009 
Matt Stover University of Texas at Austin 
Volumes of Picard modular surfaces
Picard modular surfaces are the noncompact arithmetic complex hyperbolic
2orbifolds. I will prove that the two orbifolds studied by John Parker as
candidates for orbifolds of smallest volume are indeed the unique
arithmetic complex hyperbolic 2orbifolds of minimal volume. Given time, I
will also make some remarks on finding minimal volume manifolds.

May 6, 2009 
Valerio Pascucci Scientific Computing and Imaging Institute, University of Utah 
Multiscale Morse Theory for Scientific Data Analysis
Advanced techniques for understanding large scale scientific data are
a crucial ingredient in modern science discovery. Developing such
techniques involves a number of major challenges in management of
massive data, and quantitative analysis of scientific features of
unprecedented complexity. Addressing these challenges requires
interdisciplinary research in diverse topics including the
mathematical foundations of data representations, algorithmic design,
and the integration with applications in physics, biology, or
medicine.
In this talk, I will present a set of case in the use of Morse theory
for the representation and analysis of largescale scientific data.
Due to the combinatorial nature of the approach, we can implement the
core constructs of Morse theory without the approximations and
instabilities of classical numerical techniques. We use topological
cancellations to build multiscale representations that capture local
and global trends present in the data. The inherent robustness of our
combinatorial algorithms allows us to address the high complexity of
the feature extraction problem for highresolution scientific data.

Current seminar Archive of past talks
Max Dehn Seminar is organized by Mladen Bestvina, Ken Bromberg, Patrick Reynolds,
Jing Tao, Domingo Toledo, and Kevin Wortman.
This web page is maintained by Patrick Reynolds and Jing Tao.