Past Events

E.g., Jun 3, 2024

Alan Chang

Washington University in St. Louis
Venetian blinds, digital sundials, and efficient coverings

March 11, 2024

ESB 4133 (PIMS library)

Davies's efficient covering theorem states that we can cover any measurable set in the plane by lines without increasing the total measure. This result has a dual formulation, known as Falconer's digital sundial theorem, which states that we can construct a set in the plane to have any desired... Read more

  • Harmonic Analysis and Fractal Geometry

Michael Bennett

UBC
Arithmetic progressions in sumsets of geometric progressions

March 7, 2024

ESB 4133

If A and B are two geometric progressions, we characterize all 3-term arithmetic progressions in the sumset A+B. Somewhat surprisingly, while mostly elementary, this appears to require quite deep machinery from Diophantine Approximation. Read more

  • Number Theory

David Popović

UCLA
Algebraic structure of knot Floer homology

March 6, 2024

ESB 4133 (PIMS lounge)

Knot Floer homology is a powerful link invariant. In its most general version, it is a bigraded chain complex over a polynomial ring F[U,V]. In this talk, I will describe the structure theorem of such objects - they are a direct sum of snake complexes and local systems - and explain what... Read more

  • Topology

Mathav Murugan

UBC
Boundary trace of reflected diffusions

March 6, 2024

ESB 4127

Spitzer (1958) showed that the trace of reflected Brownian motion on the upper half space on its boundary is a Cauchy process. More generally, every symmetric stable process in n-dimensional Euclidean space can be obtained as a trace process of a diffusion in the (n+1)-dimensional upper half-... Read more

  • Probability

Shaoming Guo

UW Madison
The dichotomy of Nikodym sets and local smoothing estimates

March 6, 2024

MATX 1118

The talk is about local smoothing estimates for linear wave equations and the existence of Nikodym sets. We will see that they form a dichotomy: Local smoothing estimates hold if and only if Nikodym sets do not exist. Read more

  • Harmonic Analysis and Fractal Geometry

Aryan Tajmir Riahi & Wanxin Li

UBC, Computer Science
Optimal Transport-based methods and algorithms for density maps alignment in Cryo-EM and transfer learning of Electronic Health Records

March 6, 2024

ESB 4133

Recent advances in computational transport have led to powerful applications in various domains. We will present here two recent methods and algorithms that leverage the evaluation of Wasserstein distances and barycentric projections from transport maps to: (1) find a rigid body transformation... Read more

  • Mathematical Biology

Danny Ofek

UBC
Essential dimension of cohomology classes via valuation theory

March 4, 2024

MATH 126

Informally speaking, the essential dimension of an algebraic object is the minimal number of independent parameters needed to define it. We will explain how valuations can be used to prove lower bounds on the essential dimension of Galois cohomology classes of a field (with an emphasis on the... Read more

  • Algebra and Algebraic geometry

SEGISMUNDO IZQUIERDO

Universidad de Valladolid
Repeated games with endogenous separation

March 1, 2024

ESB 1012 (PIMS building)

A game represents an interaction in which a group of players make individual choices and receive individual payoffs that depend on the aggregate set of choices. We consider indefinitely repeated games with endogenous separation (meaning that players can dissolve their current group of co-players... Read more

Giuseppe Genovese

University of Zürich
Landscape complexity, random determinants and spin glasses

March 1, 2024

(online talk)

An important object in the study of high-dimensional non-convexf unctions is the so-called complexity, defined as the logarithm of the number of critical points. For random functions, this ist ypically obtained by the Kac-Rice formula, which requires in particular the computation of certain... Read more

Kim Klinger-Logan

Kansas State University
A shifted convolution problem arising from physics

February 29, 2024

ESB 4127

Certain eigenvalue problems involving the invariant Laplacian on moduli spaces have potential applications to scattering problems in physics. Green, Russo, Vanhove, et al., discovered the behavior of gravitons (hypothetical particles of gravity represented by massless string states) is also... Read more

  • Number Theory