Kamyrn Spinelli (Queen's University)

Date

Tuesday April 21, 2026
10:30 am - 12:00 pm

Location

Jeffrey Hall, Room 222

Calabi-Yau Manifolds Seminar

Speaker: Kamryn Spinelli (Queen's University)

Title: A beginner's introduction to hypergeometric motives

Abstract: In this talk, we will give a brief introduction to the theory of hypergeometric motives, following the 2021 expository article of Roberts-Rodriguez-Villegas and the new paper by Madriaga-Pacetti-Rodriguez-Villegas released just last month. We will also touch on the definition and meaning of the motivic Galois group as described in the 2001 survey article of Kontsevich-Zagier on periods.

Portia Anderson (Queen's University)

Date

Wednesday April 1, 2026
12:30 pm - 1:30 pm

Location

Jeffrey Hall, Room 102

Curves Seminar

Speaker: Portia Anderson (Queen's University)

Title: Intro to Schubert Calculus

Abstract: We will continue our discussion of the Schubert varieties and the cohomology ring of the Grassmannian. Schubert calculus is about computing the structure constants of this ring, which happen to be the Littlewood-Richardson numbers. We will recall methods we have seen so far for finding the Littlewood-Richardson numbers, as well as introducing a new way using puzzles. If time permits, we will extend our discussion to Schubert calculus in d-step flag varieties.

Emine Yıldırım (ICMS)

Date

Monday March 30, 2026
3:00 pm - 4:00 pm

Location

Jeffery Hall, Room 422

Algebra & Geometry Seminar

Speaker: Emine Yıldırım (The International Center for Mathematical Sciences (ICMS) - Sofia)

Title: Lattices from representation theory of algebras

Abstract: Torsion theories give rise to nice lattice structures in abelian categories. Pretorsion theories were recently introduced as a non-pointed analogue, allowing torsion-theoretic methods to be extended to broader categorical settings. In this talk, we investigate pretorsion classes in the module category of a finite-dimensional algebra and prove that they are naturally organized into a lattice under inclusion. We further analyze when this lattice is distributive and compare it with the classical lattice of torsion classes.This is joint work with Federico Campanini and Francesca Fedele.

Abdullah Zubair (Queen's University)

Date

Wednesday March 25, 2026
12:30 pm - 1:30 pm

Location

Jeffrey Hall, Room 102

Curves Seminar

Speaker: Abdullah Zubair (Queen's University)

Title: Schubert Varieties. Cohomology groups of the Grassmannian

Abstract: We’ll begin by introducing Schubert Varieties and Schubert Cells. After exploring a few examples, we’ll attempt to construct the cohomology groups of the Grassmannian and hopefully see some interplay between the combinatorics of young tableaux and the information encoded in the cohomology groups.

Kamyrn Spinelli (Queen's University)

Date

Wednesday March 25, 2026
10:30 am - 12:00 pm

Location

Jeffrey Hall, Room 222

Calabi-Yau Manifolds Seminar

Speaker: Kamryn Spinelli (Queen's University)

Title: What's Calabi-Yau about Calabi-Yau modular forms?, part 2

Abstract: Connections between elliptic curves and modular forms have been well-known for many years. The analogous picture in higher dimensions is less clear even though there is strong evidence, especially in the context of mirror symmetry, that these physically-motivated geometric objects (Calabi-Yau varieties) and arithmetic objects (modular forms and their generalizations) know something about each other. In a sequence of articles beginning in 2011, Movasati initiated a program to systematically understand these connections in the case of quintic threefolds. Toward this end, he introduced a generalization of modular forms called (differential) Calabi-Yau modular forms. In this talk, we will survey the ingredients in the context of elliptic curves, before turning to the quintic threefold and Movasati's definition of Calabi-Yau modular forms.

Yang Zheng (UC Sand Diego)

Date

Friday March 27, 2026
2:30 pm - 3:20 pm

Location

Jeffery Hall, Room 234

Department Colloquium

Speaker: Yang Zheng (UC Sand Diego)

Title: Extended Convex Lifting for Policy Optimization in Control

Abstract:
Direct policy search has achieved great empirical success in reinforcement learning. Many recent studies have revisited its theoretical foundation for continuous control, which reveals elegant nonconvex geometry in various benchmark problems. In this talk, we introduce an Extended Convex Lifting (ECL) framework, which reveals hidden convexity in classical optimal and robust control problems from a modern optimization perspective. Our ECL offers a bridge between nonconvex policy optimization and convex reformulations. Despite non-convexity and non-smoothness, the existence of an ECL not only reveals that minimizing the original function is equivalent to a convex problem, but also certifies a class of first-order non-degenerate stationary points to be globally optimal. We believe that the ECL framework may be of independent interest for analyzing nonconvex problems beyond control.

Calvin Fletcher (Queen's University)

Date

Wednesday March 18, 2026
12:30 pm - 1:30 pm

Location

Jeffrey Hall, Room 102

Curves Seminar

Speaker: Calvin Fletcher (Queen's University)

Title: An introduction to line bundles and an application to representation theory

Abstract: In this talk we will deviate slightly from the notes in order to introduce line bundles. We will see a few constructions of them and also study what are known as sections of line bundles. Next, we will move back into the world of flag varieties in order to study a particular construction of line bundles over flag varieties. Using this construction, we will achieve another realization of the irreducible representations of the general linear group.

Kamyrn Spinelli (Queen's University)

Date

Wednesday March 18, 2026
10:30 am - 12:00 pm

Location

Jeffrey Hall, Room 222

Calabi-Yau Manifolds Seminar

Speaker: Kamryn Spinelli (Queen's University)

Title: What's Calabi-Yau about Calabi-Yau modular forms?

Abstract: Connections between elliptic curves and modular forms have been well-known for many years. The analogous picture in higher dimensions is less clear even though there is strong evidence, especially in the context of mirror symmetry, that these physically-motivated geometric objects (Calabi-Yau varieties) and arithmetic objects (modular forms and their generalizations) know something about each other. In a sequence of articles beginning in 2011, Movasati initiated a program to systematically understand these connections in the case of quintic threefolds. Toward this end, he introduced a generalization of modular forms called (differential) Calabi-Yau modular forms. In this talk, we will survey the ingredients in the context of elliptic curves, before turning to the quintic threefold and Movasati's definition of Calabi-Yau modular forms.