# MSCS Seminar Calendar

Monday August 25, 2014

Friday August 29, 2014

Wednesday September 3, 2014

**Statistics Seminar**

Stat Wars Episode VI: Return of the Fiducialist

Keli Liu (Stanford University)

4:00 PM in SEO 636

Priors are the path to the dark side. Fisher developed the Fiducial argument to obtain prior free "posterior" inferences but at the
seeming cost of violating basic probability laws. Was Fisher crazy or did madness mask innovation? Fiducial calculations can be
easily understood through the missing-data perspective which illuminates for us that the Fiducial "posterior" is in fact a prior updated
not with the full data likelihood, but a

*partial*likelihood in the spirit of Cox regression. Just as Cox regression arose from a need to render inferences robust to an unknown hazard function, so Fiducial inferences are insensitive to the prior. While Statistics has fixated two extremes---fully conditional (but fragile) Bayesian inferences or unconditional (but robust) Frequentist inferences---a compromise via partial conditioning has gone ignored. Surely, the middle ground is more fiducial than either extreme.Monday September 8, 2014

**Geometry, Topology and Dynamics Seminar**

von Neumann algebras of negatively curved groups

Thomas Sinclair (UCLA)

3:00 PM in SEO 636

Negatively curved groups have long been and continue to be one of the most intensely studied classes of discrete groups. These groups have also played an important role in functional analysis, notably via K-theory and the Baum-Connes conjecture. In this talk I will survey some recent results in the classification of von Neumann algebras generated by negatively curved groups and their measurable actions. I will explain how negative curvature is central to these results in terms of a broad, cohomogical-type property such groups possess. As an application, I will show how these techniques generalize some results on the measurable dynamics of hyperbolic groups. No knowledge of von Neumann algebras will be assumed.

**Applied Mathematics Seminar**

Modeling tuberculosis, from cells to populations

Leonid Chindelevitch (Harvard School of Public Health)

4:00 PM in SEO 636

Tuberculosis continues to afflict millions of people and causes over a million deaths a year worldwide. Multi-drug resistance is also on the rise, causing concern among public-health experts. This talk will give an overview of my work on modeling tuberculosis at various scales. On the cellular side I will describe models of the metabolism of M. tuberculosis, where insights from duality led to a consistent analysis of existing models, a systematic method for reconciling discrepant models, and the identification of putative drug targets. On the population side I will describe models of strain evolution, where a new metric combined with an optimization-based approach resulted in an accurate classification of complex infections as originating from mutation or mixed infection, as well as the identification of the strains composing these complex infections.

Tuesday September 9, 2014

**Logic Seminar**

Existentially closed C*-algebras

Thomas Sinclair (UCLA)

4:00 PM in SEO 427

A C*-algebra A is said to be existentially closed if, roughly, every set of equations involving norms of noncommutative *-polynomials which has a solution in B(H) has a sequence of approximate solutions in A. A basic result in continuous logic shows that every separable C*-algebra is contained in a separable, existentially closed C*-algebra. In this talk I will survey some basic properties of existentially closed C*-algebras. In particular I will describe how existential closure is deeply connected to several open problems in C*-algebras such as Kirchberg's problem on whether every separable C*-algebra embeds in an ultrapower of the Cuntz algebra O_2, as well as Kirchberg's C*-algebraic reformulation of of Connes' embedding problem. This talk is based on joint work with Isaac Goldbring.

Monday September 15, 2014

Monday September 22, 2014

**Applied Mathematics Seminar**

Soft metrics for decision analysis under uncertainty

Michelle Quirk (National Intelligence University and National Geospatial-Intelligence Agency)

4:00 PM in SEO 636

Modern decision making challenges the human capacity to reason in an
environment of uncertainty, imprecision, and incompleteness of
information. Probability measures are not well-suited when the evidence
is scarce and unreliable. Built from fuzzy sets, possibility metrics
overcomes some of the restrictions and insufficiencies of probabilities,
in a complementary, yet not competitive manner. We show the theoretical
foundation and the interdisciplinary approach required to devise soft
metrics as attributes of decision criteria that cannot be expressed
numerically. This talk concludes with an example of soft metrics used in
real-world ranking exercises.

Friday September 26, 2014

Monday September 29, 2014

**Geometry, Topology and Dynamics Seminar**

Hausdorff dimension in graph matchbox manifolds

Olga Lukina (UIC)

3:00 PM in SEO 636

A lamination is a compact connected metric space, where each point has a neighborhood homeomorphic to the product of a Euclidean disc and a totally disconnected space. Given a lamination, one can ask if this lamination can be realised as a subset of a smooth foliated finite-dimensional manifold, so that the leaves of the lamination are contained in the leaves of the foliation of the manifold. More precisely, one asks if there exists a foliated embedding of a given lamination into a smooth foliated manifold by a bi-Lipschitz homeomorphism.
Hausdorff dimension provides an obstruction to the existence of such an embedding. In the talk, we study a specific class of laminations, called graph matchbox manifolds, obtained as suspensions of pseudogroup actions on the space of pointed trees. We give examples of such laminations which have infinite Hausdorff dimension of their transversals, and, therefore, cannot be embedded as a subset of a smooth foliation of a finite-dimensional manifold by a bi-Lipschitz homeomorphism.

Monday October 6, 2014

Wednesday October 8, 2014

Monday October 13, 2014

Wednesday October 15, 2014

**Distinguished Lecture Series**

The "P vs. NP" problem: efficient computation, Internet security, and the limits to human knowledge

Avi Wigderson (Institute for Advanced Study)

4:00 PM in TBA

The "P vs. NP" problem, formulated by computer theorists in the 1970s, quickly became a central outstanding problem
of science and mathematics. In this talk I will attempt to describe its mathematical, scientific and philosophical
content. I will discuss its status, and the implications of its resolution on science and technology (making clear
that the \$1M prize on solving it pales in comparison with these implications).
No special background will be assumed.

Thursday October 16, 2014

**Distinguished Lecture Series**

Randomness

Avi Wigderson (Institute for Advanced Study)

3:00 PM in SEO 636

Is the universe inherently deterministic or probabilistic? Perhaps more importantly - can we tell the difference
between the two?
Humanity has pondered the meaning and utility of randomness for millennia.
There is a remarkable variety of ways in which we utilize perfect coin tosses to our advantage:
in statistics, cryptography, game theory, algorithms, gambling... Indeed, randomness seems indispensable!
Which of these applications survive if the universe had no randomness in it at all? Which of them survive
if only poor quality randomness is available, e.g. that arises from "unpredictable" phenomena like the
weather or the stock market?
A computational theory of randomness, developed in the past three decades, reveals (perhaps counter-intuitively)
that very little is lost in such deterministic or weakly random worlds. In the talk I'll explain the main ideas
and results of this theory.
The talk is aimed at a general scientific audience.

Friday October 17, 2014

**Distinguished Lecture Series**

Permanent & Determinant: non-identical twins

Avi Wigderson (Institute for Advanced Study)

3:00 PM in SEO 636

The determinant is undoubtedly the most important polynomial function in mathematics.
Its lesser known sibling, the permanent, plays very important roles in
enumerative combinatorics, statistical and quantum physics, and the
theory of computation. In this lecture I plan to survey some of the
remarkable properties of the permanent, its applications and impact on
fundamental computational problems, its similarities to and apparent
differences from the determinant, and how these relate to the P vs. NP
prolem.
This lecture is intended to a general Math & CS audience.

Monday October 20, 2014

Wednesday October 22, 2014

Monday October 27, 2014

Friday November 7, 2014

Monday November 10, 2014