seminars fall99

seminar
date / time
speaker
topic

Algebra

Tues. Aug. 31
2:10-3:00 RH211

J. Sheth

On multiplicity-free permutation representations.

Topology / Diff. Geom.

Tues. Aug. 31
3:15-4:15 RH211

A. Bart

Geometric sums of (immersed) quasi-fuchsian surfaces. (preliminary report)

Abstract: If a complete hyperbolic 3-manifold contains two injective non-commensurable quasi-fuchsian surfaces, which meet in sufficiently large angles,have large patches, and are in minimal intersection form, then the geometric sum of these two surfaces is a collection of injective, quasi-fuchsian surfaces.

Algebra

Tues. Sep 7
2:10-3:00 RH211

J. Sheth

On multiplicity-free permutation representations. (cont'd)

Topology / Diff. Geom.

Tues. Sep 7
3:15-4:15 RH211

A. Bart

Geometric sums of (immersed) quasi-fuchsian surfaces. (preliminary report) Cont'd.

Algebra

Tues. Sep 14
2:10-3:00 RH211

J. Sheth

"Decomposing Induced Modules with Hecke Algebras."

Topology / Diff. Geom.

Tues. Sep 14
3:15-4:15 RH211

Dr. S. Fenley
Washinton Univ.

"Transversality: pseudo-Anosov flows and topology of foliations"

Algebra

Tues. Sep 21
2:10-3:00 RH211

Joanne Redden

Nonabelian Tensor Products

Topology / Diff. Geom.

Tues. Sep 21
3:15-4:15 RH211

K. Scannell

3-manifolds which are spacelike slices of flat spacetimes I

Abstract: 3-manifolds which are spacelike slices of flat spacetimes, I and II
We will be concerned with spacetimes of the form M^3 x R, where M^3 is a closed connected 3-manifold, the slices M^3 x t are spacelike, and the spacetime metric is flat. The main result determines exactly which M^3's arise -- roughly M is hyperbolic or else has a finite cover of the form (surface x S^1). The first talk will be devoted primarily to surveying what is known about classifying closed 3-manifolds. The second talk will sketch the proof of the main theorem, which relies on powerful `homotopy equivalence => homeomorphism' results for 3-manifolds due to Waldhausen, Scott, Mess, Gabai, and others

Algebra

Tues. Sep 21
2:10-3:00 RH211

Joanne Redden

Nonabelian Tensor Products (Cont'd)

Topology / Diff. Geom.

Tues. Sep 28
3:15-4:15 RH211

K. Scannell

3-manifolds which are spacelike slices of flat spacetimes II

Analysis

Tues. Oct 5
1:30 RH128

B. Currey

Distributions in Plancherel Theory

Algebra

Tues. Oct.5
2:10-3:00 RH211

Joanne Redden

Nonabelian Tensor Products (Cont'd)

Topology / Diff. Geom.

Tues. Oct 5
3:15-4:15 RH211

Dr. I. Redmount
(Physics Dept.)

"Defining Physics in Spatially Hyperbolic Friedmann-Robertson-Walker Spacetimes."

Analysis

Tues. Oct 12
1:30 RH128

B. Currey

Distributions in Plancherel Theory (Cont'd)

Algebra

Tues. Oct.12
2:10-3:00 RH211

David Jackson

Presentations of Nilpotent Groups

Colloquium

Thurs. Oct. 14
3:00-4:00 RH223

Dr Eugene Seneta
Univ. of Sydney, Australia

Markov and the Birth of Chain Dependence

There will be refreshments served, starting at 2:30 pm in the Mathematics lounge prior to the talk.

Abstract: Markov chains, introduced by the Russian mathematician A.A. Markov in 1906, have become widely known and generalized as probability models. Virtually unknown is the fact that Markov, of the Saint Petersburg Mathematical "School", was prompted to introduce his chains in response to the Moscow mathematician P.A. Nekrasov, with whom Markov was involved in a series of bitter disputes. These involved not only mathematical issues, but also philosophical and religious concepts, whereby they acquired ideological coloration through the Sovieet era and helped lead to the political suppression of the mathematical achievements of the Moscow Mathematical "School".
This talk will explore these issues briefly from the focal point of the Weak Law of Large Numbers as empirical fact and mathematical theorem.

Tues. Oct 19

Spring Break

Analysis

Tues. Oct 26
1:30 RH128

Darrin Speegle

A survey of Dvoretzky's Theorem.

Abstract: Dvoretzky's Theorem states (in one form) that every centrally symmetric convex body contains a cross-section of large dimension that is almost a sphere, a fact that is not immediately apparent (to most people) even for cubes or other bodies with finitely many extreme points.
I will discuss a proof of this fact which involves geometry, probability and functional analysis, and I will discuss at least one application of the theorem.
Please note that this talk will only contain material that has been known for at least 20 years, and I will start with the basics.

Algebra

Tues. Oct.26
2:10-3:00 RH211

David Jackson

Presentations of Nilpotent Groups

Topology / Diff. Geom

Tues. Oct 26
3:15-4:15 RH211

Christine Stevens

"Differential geometry, Galois theory, and Lie's theory of transformation groups"

Topology / Diff. Geom

Tues. Nov 2
3:15-4:15 RH211

Christine Stevens

"Differential geometry, Galois theory, and Lie's theory of transformation groups"

Algebra

Thurs. Nov 11
2:00-3:00 RH211

Anneke Bart

Bianchi Groups I

Analysis

Tues. Nov 16
1:30 RH128

Kevin Scannell

"Harmonic maps, deformations, and rigidity"

Abstract: I will spend most of the time explaining in general terms how harmonic mappings are used to understand rigidity of geometric structures, and hopefully explain some of the analytic difficulties which arise in my work on Teichmuller theory with M. Wolf.

Topology / Diff. Geom.

Tues. Nov 16
3:15-4:15 RH211

Dr. L.Conlon
Washinton Univ.

Topology of Generic Leaves.

Algebra

Thurs. Nov 18
2:10-3:00 RH142

Kevin Scannell

Bianchi Groups II

Colloqium

Thurs. Nov 18
4:00-5:00 RH223

Dr. L. Kauffman
UI, Chicago

Rational Knots, Tangles, and DNA

Abstract: Rational knots are obtained by closing rational tangles, and rational tangles are a class of tangles that can be studied by direct means. In this talk we will prove a theorem that classifies rational tangles using elementary methods due to the speaker and Jay Goldman. We then classify rational knots by elementary arguments due to the speaker and Sofia Lambropoulou. We will show how this aspect of knot theory is relevant to the study of fractions, continued fractions, games with strings,and the molecular topology of DNA.
Refreshments: 3:30 pm in the Math-CS Lounge.

Topology / Diff. Geom.

Fri. Nov 19
4:00-5:00 RH211

Dr. L. Kauffman
UI, Chicago

Virtual Knot Theory

Topology / Diff. Geom

Tues. Nov 23
3:15-4:15 RH211

Dr.L.Conlon
Washinton Univ.

Topology of Generic Leaves. Part II

seminar	date / time	speaker	topic
Algebra	Tues. Aug. 31 2:10-3:00 RH211	J. Sheth	On multiplicity-free permutation representations.
Topology / Diff. Geom.	Tues. Aug. 31 3:15-4:15 RH211	A. Bart	Geometric sums of (immersed) quasi-fuchsian surfaces. (preliminary report)
Abstract: If a complete hyperbolic 3-manifold contains two injective non-commensurable quasi-fuchsian surfaces, which meet in sufficiently large angles,have large patches, and are in minimal intersection form, then the geometric sum of these two surfaces is a collection of injective, quasi-fuchsian surfaces.
Algebra	Tues. Sep 7 2:10-3:00 RH211	J. Sheth	On multiplicity-free permutation representations. (cont'd)
Topology / Diff. Geom.	Tues. Sep 7 3:15-4:15 RH211	A. Bart	Geometric sums of (immersed) quasi-fuchsian surfaces. (preliminary report) Cont'd.
Algebra	Tues. Sep 14 2:10-3:00 RH211	J. Sheth	"Decomposing Induced Modules with Hecke Algebras."
Topology / Diff. Geom.	Tues. Sep 14 3:15-4:15 RH211	Dr. S. Fenley Washinton Univ.	"Transversality: pseudo-Anosov flows and topology of foliations"
Algebra	Tues. Sep 21 2:10-3:00 RH211	Joanne Redden	Nonabelian Tensor Products
Topology / Diff. Geom.	Tues. Sep 21 3:15-4:15 RH211	K. Scannell	3-manifolds which are spacelike slices of flat spacetimes I
Abstract: 3-manifolds which are spacelike slices of flat spacetimes, I and II We will be concerned with spacetimes of the form M^3 x R, where M^3 is a closed connected 3-manifold, the slices M^3 x t are spacelike, and the spacetime metric is flat. The main result determines exactly which M^3's arise -- roughly M is hyperbolic or else has a finite cover of the form (surface x S^1). The first talk will be devoted primarily to surveying what is known about classifying closed 3-manifolds. The second talk will sketch the proof of the main theorem, which relies on powerful `homotopy equivalence => homeomorphism' results for 3-manifolds due to Waldhausen, Scott, Mess, Gabai, and others
Algebra	Tues. Sep 21 2:10-3:00 RH211	Joanne Redden	Nonabelian Tensor Products (Cont'd)
Topology / Diff. Geom.	Tues. Sep 28 3:15-4:15 RH211	K. Scannell	3-manifolds which are spacelike slices of flat spacetimes II
Analysis	Tues. Oct 5 1:30 RH128	B. Currey	Distributions in Plancherel Theory
Algebra	Tues. Oct.5 2:10-3:00 RH211	Joanne Redden	Nonabelian Tensor Products (Cont'd)
Topology / Diff. Geom.	Tues. Oct 5 3:15-4:15 RH211	Dr. I. Redmount (Physics Dept.)	"Defining Physics in Spatially Hyperbolic Friedmann-Robertson-Walker Spacetimes."
Analysis	Tues. Oct 12 1:30 RH128	B. Currey	Distributions in Plancherel Theory (Cont'd)
Algebra	Tues. Oct.12 2:10-3:00 RH211	David Jackson	Presentations of Nilpotent Groups
Colloquium	Thurs. Oct. 14 3:00-4:00 RH223	Dr Eugene Seneta Univ. of Sydney, Australia	Markov and the Birth of Chain Dependence
There will be refreshments served, starting at 2:30 pm in the Mathematics lounge prior to the talk.
Abstract: Markov chains, introduced by the Russian mathematician A.A. Markov in 1906, have become widely known and generalized as probability models. Virtually unknown is the fact that Markov, of the Saint Petersburg Mathematical "School", was prompted to introduce his chains in response to the Moscow mathematician P.A. Nekrasov, with whom Markov was involved in a series of bitter disputes. These involved not only mathematical issues, but also philosophical and religious concepts, whereby they acquired ideological coloration through the Sovieet era and helped lead to the political suppression of the mathematical achievements of the Moscow Mathematical "School". This talk will explore these issues briefly from the focal point of the Weak Law of Large Numbers as empirical fact and mathematical theorem.
	Tues. Oct 19		Spring Break
Analysis	Tues. Oct 26 1:30 RH128	Darrin Speegle	A survey of Dvoretzky's Theorem.
Abstract: Dvoretzky's Theorem states (in one form) that every centrally symmetric convex body contains a cross-section of large dimension that is almost a sphere, a fact that is not immediately apparent (to most people) even for cubes or other bodies with finitely many extreme points. I will discuss a proof of this fact which involves geometry, probability and functional analysis, and I will discuss at least one application of the theorem. Please note that this talk will only contain material that has been known for at least 20 years, and I will start with the basics.
Algebra	Tues. Oct.26 2:10-3:00 RH211	David Jackson	Presentations of Nilpotent Groups
Topology / Diff. Geom	Tues. Oct 26 3:15-4:15 RH211	Christine Stevens	"Differential geometry, Galois theory, and Lie's theory of transformation groups"
Topology / Diff. Geom	Tues. Nov 2 3:15-4:15 RH211	Christine Stevens	"Differential geometry, Galois theory, and Lie's theory of transformation groups"
Algebra	Thurs. Nov 11 2:00-3:00 RH211	Anneke Bart	Bianchi Groups I
Analysis	Tues. Nov 16 1:30 RH128	Kevin Scannell	"Harmonic maps, deformations, and rigidity"
Abstract: I will spend most of the time explaining in general terms how harmonic mappings are used to understand rigidity of geometric structures, and hopefully explain some of the analytic difficulties which arise in my work on Teichmuller theory with M. Wolf.
Topology / Diff. Geom.	Tues. Nov 16 3:15-4:15 RH211	Dr. L.Conlon Washinton Univ.	Topology of Generic Leaves.
Algebra	Thurs. Nov 18 2:10-3:00 RH142	Kevin Scannell	Bianchi Groups II
Colloqium	Thurs. Nov 18 4:00-5:00 RH223	Dr. L. Kauffman UI, Chicago	Rational Knots, Tangles, and DNA
Abstract: Rational knots are obtained by closing rational tangles, and rational tangles are a class of tangles that can be studied by direct means. In this talk we will prove a theorem that classifies rational tangles using elementary methods due to the speaker and Jay Goldman. We then classify rational knots by elementary arguments due to the speaker and Sofia Lambropoulou. We will show how this aspect of knot theory is relevant to the study of fractions, continued fractions, games with strings,and the molecular topology of DNA. Refreshments: 3:30 pm in the Math-CS Lounge.
Topology / Diff. Geom.	Fri. Nov 19 4:00-5:00 RH211	Dr. L. Kauffman UI, Chicago	Virtual Knot Theory
Topology / Diff. Geom	Tues. Nov 23 3:15-4:15 RH211	Dr.L.Conlon Washinton Univ.	Topology of Generic Leaves. Part II