Previous Conferences & Workshops

Apr
19
2016

Analysis Seminar

Spectral gaps via additive combinatorics
Semyon Dyatlov
3:15pm|S-101

A spectral gap on a noncompact Riemannian manifold is an asymptotic strip free of resonances (poles of the meromorphic continuation of the resolvent of the Laplacian). The existence of such gap implies exponential decay of linear waves, modulo a...

Apr
19
2016

Computer Science/Discrete Mathematics Seminar II

A characterization of functions with vanishing averages over products of disjoint sets
10:30am|S-101

We characterize all complex-valued (Lebesgue) integrable functions $f$ on $[0,1]^m$ such that $f$ vanishes when integrated over the product of $m$ measurable sets which partition $[0,1]$ and have prescribed Lebesgue measures $\\alpha_1,\\ldots,\...

Apr
15
2016

Joint IAS/Princeton University Symplectic Geometry Seminar

Symplectic embeddings and infinite staircases
Ana Rita Pires
10:30am|S-101

McDuff and Schlenk studied an embedding capacity function, which describes when a 4-dimensional ellipsoid can symplectically embed into a 4-ball. The graph of this function includes an infinite staircase determined by the odd index Fibonacci numbers...

Apr
14
2016

Joint IAS/Princeton University Number Theory Seminar

Optimal strong approximation for quadratic forms
4:30pm|Fine 214, Princeton University

For a non-degenerate integral quadratic form $F(x_1, \dots , x_d)$ in 5 (or more) variables, we prove an optimal strong approximation theorem. Fix any compact subspace $\Omega\subset\mathbb{R}^d$ of the affine quadric $F(x_1,\dots,x_d)=1$. Suppose...

Apr
14
2016

Geometric Structures on 3-manifolds

A graph coloring problem and its algebraic and topological consequences
Daniel Wise
2:00pm|S-101

I will first describe a simple graph coloring problem and survey some examples of graphs for which the coloring problem has or has no solution. I will then give a quick introduction to Bestvina-Brady Morse theory. Finally, I will describe the...

Apr
12
2016

Geometric Structures on 3-manifolds

Veering Dehn surgery
Saul Schleimer
2:00pm|S-101

(Joint with Henry Segerman.) It is a theorem of Moise that every three-manifold admits a triangulation, and thus infinitely many. Thus, it can be difficult to learn anything really interesting about the three-manifold from any given triangulation...

Apr
11
2016

Members’ Seminar

Applications of thin orbits
2:00pm|S-101

We will discuss some natural problems in arithmetic that can be reformulated in terms of orbits of certain "thin" (semi)groups of integer matrix groups.

Apr
09
2016

Workshop on Topology: Identifying Order in Complex Systems

A topological predictor of protein compressibility
5:00pm|David Rittenhouse Laboratory Room A4, University of Pennsylvania

A standard question in contemporary proteomics asks which properties of proteins may be directly inferred from their molecular structure. Using only X-Ray crystallography data (of the type which is cataloged in the Protein Data Bank), I will outline...

Apr
09
2016

Workshop on Topology: Identifying Order in Complex Systems

Metrics on the space of shapes, and applications to biology
3:30pm|David Rittenhouse Laboratory Room A4, University of Pennsylvania

The problem of comparing shapes turns up in different guises in numerous fields. I will discuss a new metric on the space of smooth Riemannian 2-spheres that is well suited for comparing geometric similarity. The metric is based on a distortion...