Kasia Jankiewicz (University of California Santa Cruz)

Date

Friday October 21, 2022
2:30 pm - 3:30 pm

Location

Jeffery Hall, Room 234

Math & Stats Department Colloquium

Kasia Jankiewicz

Friday, October 21st, 2022

Time: 2:30 p.m.  Place: Jeffery Hall, Room 234

Speaker: Kasia Jankiewicz (University of California Santa Cruz)

Title: Questions about Artin groups

Abstract: Artin groups are a family of infinite discrete groups that includes free groups, free abelian groups, and braid groups. They are closely related to Coxeter groups. They are defined by simple-looking presentations, but their geometry is mysterious, and many basic questions about them remain open. I will discuss some of my contributions to understanding Artin groups.

Kasia is an Assistant Professor at the University of California Santa Cruz. Previously she was an L.E. Dickson Instructor at the University of Chicago, and a Research Member at the MSRI program Random and Arithmetic Structures in Topology. She completed her PhD at McGill University in 2018, under the supervision of Piotr Przytycki and Daniel Wise. She holds an NSF grant, has held AWM-NSF and AMS-Simons Travel grants, and will be visiting the CRM in the winter as a CRM-Simons Scholar in Residence. Broadly speaking, Kasia's research is in geometric group theory. She is particularly interested in non-positive curvature, cube complexes, Artin groups, Coxeter groups, random groups, small cancellation theories, separability properties, algebraic bering and coherence.

Debaditya Raychaudhary (Fields Institue)

Date

Monday October 24, 2022
4:30 pm - 5:30 pm

Location

TBA

Algebra & Geometry Seminar

Monday, October 24th, 2022

Time: 4:30 p.m.  Place: TBA

Speaker: Debaditya Raychaudhary (Fields Institue)

Title: Continuous CM-regularity and generic vanishing

Abstract:

Website details here: https://mast.queensu.ca/~georep/Fall%20'22.html

Mirko Degli Esposti (Università di Bologna, Italy)

Date

Friday October 21, 2022
10:00 am - 11:00 am

Location

Jeffery Hall, Room 422

Dynamics, Geometry and Groups Seminar

Friday, October 21st, 2022

Time: 10:00 a.m.  Place: Jeffery Hall, Room 422

Speaker: Mirko Degli Esposti (Università di Bologna, Italy)

Title: Recurrence times, waiting times and universal entropy production estimators

Abstract: The universal typical-signal estimators of entropy and cross entropy based on the asymptotics of recurrence and waiting times play an important role in information theory. Building on their construction, we introduce and study universal typical-signal estimators of entropy production in the context of nonequilibrium statistical mechanics of one-sided shifts over finite alphabets. We will discuss some applications to DNA sequences.

Federico Salmoiraghi (Queen's University)

Date

Friday October 7, 2022
10:00 am - 11:00 am

Location

Jeffery Hall, Room 422

Dynamics, Geometry and Groups Seminar

Friday, October 7th, 2022

Time: 10:00 a.m.  Place: Jeffery Hall, Room 422

Speaker: Federico Salmoiraghi (¾ÅÐãÖ±²¥)

Title: Using contact geometry to study 3-dimensional Anosov flows

Abstract: Anosov flows are an important class of dynamical systems due to their ergodic properties and structural stability. Geometrically they are defined by two transverse invariant foliations with expanding and contracting behaviors. Much of our understanding of the structure of an Anosov flow relies on the study of the leaves space of the invariant foliations. In this talk we adopt a different approach: in the early 90s Mitsumatsu first noticed that an Anosov vector field also belongs to the intersection of two transverse contact structures rotating towards each other. After giving the necessary background, I will show how to use this point of view to address questions in the theory of surgery on Anosov flows.

Alexandre (Sasha) Zotine

Date

Wednesday October 5, 2022
1:00 pm - 2:00 pm

Location

Jeffery Hall, Room 222

Curves Seminar

Wednesday, October 5th, 2022

Time: 1:00 p.m.  Place: Jeffery Hall, Room 222

Speaker: Alexandre (Sasha) Zotine

Title: Polyhedral Cones

Abstract: This talk will cover section 1.2 in CLS. To quote: "We begin with a brief discussion of rational polyhedral cones, then explain how they relate to affine toric varieties."

Abhishek Bharadwaj (Queen’s University)

Date

Tuesday October 4, 2022
2:00 pm - 3:00 pm

Location

Jeffery Hall, Room 422

Number Theory Seminar

Tuesday, October 4th, 2022

Time: 2:00 p.m.  Place: Jeffery Hall, Room 422

Speaker: Abhishek Bharadwaj (Queen’s University)

Title: Sufficient conditions for classifying algebraic integers

Abstract: A result of Corvaja and Zannier states that given an algebraic number $\alpha$, if $\Tr_{Q(\alpha)/Q}\alpha^n$ is a non-zero integer for infinitely many natural numbers $n$, then $\alpha$ is an algebraic integer. We extend this result to generalized power sums and provide some applications. This is a joint work with Veekesh Kumar, Aparmeyo Pal and Ravindranathan Thangadurai.

Neil MacVicar (Queen's University)

Date

Friday September 30, 2022
10:00 am - 11:00 am

Location

Jeffery Hall, Room 422

Dynamics, Geometry and Groups Seminar

Friday, September 30th, 2022

Time: 10:00 a.m.  Place: Jeffery Hall, Room 422

Speaker: Neil MacVicar (¾ÅÐãÖ±²¥)

Title: Multiplicative Invariance in the Complex Plane

Abstract: In the late 60s, Hillel Furstenberg proved results and made conjectures concerning the fractal nature of subsets of the unit interval that are invariant under the map that scales a real number by a positive integer r and then kills the integer part. Since then, these sets have been deeply studied. Considerably less has been said about analogous sets in the complex plane. I will review what is known for the case when r is a positive integer that scales real numbers and then introduce a notion of times b invariance in the plane where b is a Gaussian integer. The fractal dimension of these times b invariant sets will be discussed.

Sonja Ruzic

Date

Wednesday September 28, 2022
1:00 pm - 2:00 pm

Location

Jeffery Hall, Room 319

Curves Seminar

Wednesday, September 28th, 2022

Time: 1:00 p.m.  Place: Jeffery Hall, Room 319

Speaker: Sonja Ruzic

Title: Review of Affine Varieties

Abstract: We will backtrack to cover some prerequisite topics including affine varieties, the Zariski topology, the coordinate rings.

Ruiran Sun (McGill University)

Date

Monday October 3, 2022
4:30 pm - 5:30 pm

Location

TBA

Algebra & Geometry Seminar

Monday, October 3rd, 2022

Time: 4:30 p.m.  Place: TBA

Speaker: Ruiran Sun (McGill University)

Title: On slope and valuative K-semistability for big and nef birational divisors

Abstract:

Website details here: https://mast.queensu.ca/~georep/Fall%20'22.html

Nic Fellini (Queen’s University)

Date

Tuesday September 27, 2022
2:00 pm - 3:00 pm

Location

Jeffery Hall, Room 422

Number Theory Seminar

Tuesday, September 27th, 2022

Time: 2:00 p.m.  Place: Jeffery Hall, Room 422

Speaker: Nic Fellini (Queen’s University)

Title: Fermat quotients and the Ankeny-Artin-Chowla conjecture

Abstract: In 1952, Ankeny, Artin, and Chowla proved a congruence relation mod p relating the class number of the real quadratic field Q(√p), the fundamental unit of Q(√p), and some Bernoulli number. I will present joint work with Professor Murty where we generalize the results of Ankeny, Artin, and Chowla and will discuss some consequences of a conjecture related to their work.