Events

Rahim Moosa, University of Waterloo

The binding group theorem in stable theories, as a bitorsor.

Recently,  Anand Pillay and I developed the theory of binding groups in the setting of CCM — the first order theory of compact complex manifolds. But this talk will not be about that. Rather, I will talk about a somewhat streamlined and simplified presentation of the binding group theorem for stable theories (that appears in the paper with Pillay mentioned above). There is little novelty here, except maybe the bitorsorial presentation that we give (and like).

MC 5403

Spencer Cattalani, Stony Brook University

Ahlfors currents and symplectic non-hyperbolicity

Rational curves are one of the main tools in symplectic geometry and provide a bridge to algebraic geometry. Complex lines are a more general class of curve that has the potential to connect symplectic and complex analytic geometry. These curves are non-compact, which presents a serious difficulty in understanding their symplectic aspects. In this talk, I will explain how Ahlfors currents can be used to resolve this difficulty and produce a theory parallel to that of rational curves. In particular, Ahlfors currents can be constructed via a continuity method, they control bubbling of holomorphic curves, and they form a convex set.

MC 5417

Patrick Naylor, McMaster University

Doubling Gluck twists

The Gluck twist of an embedded 2-sphere in the 4-sphere is a 4-manifold that is homeomorphic but not obviously diffeomorphic to the 4-sphere. Despite considerable study, these strange manifolds have remained a long-standing source of potential counterexamples to the only remaining case of the Poincaré conjecture. In this talk, I will give an overview of this conjecture, a visual introduction to 2-dimensional knot theory, and describe conditions that guarantee that (some) Gluck twists are standard, i.e., diffeomorphic to the 4-sphere. This is based on joint work with Dave Gabai and Hannah Schwartz.

MC 5501

Stanley Xiao, University of Northern British Columbia

Elliptic curves admitting a rational isogeny of prime degree, ordered by conductor

We consider explicit parametrizations of rational points on the modular curves X_0(p) for p in {2,3,5,7}, which corresponds to elliptic curves E/Q$ admitting a rational isogeny of degree p, and consider conductor polynomials of such curves. Conductor polynomials are polynomial divisors of the discriminant which more closely approximate the conductors of elliptic curves. By using results on almost-prime values of polynomials, including recent breakthrough work of Ben Green and Mehtaab Sawhney, we count such curves whose conductors have the least number of distinct prime factors, ordered by conductor. This is joint work with Alia Hamieh and Fatma Cicek. 

MC 5417

Elan Roth, University of Waterloo

A Continuation of Random Binary Sequences

We'll return to ML- and 1-Randomness and prove their equivalence. First, we will define some necessary machinery such as information content measures and the KC theorem.

MC 5403

Paul Cusson, University of Waterloo

Moduli spaces of monopoles part 2

We continue discussing Euclidean SU(n)-monopoles, now in the case n >= 3, and we aim to describe their moduli spaces using spaces of rational maps from the projective line to flag varieties

MC 5403

Thomas Sinclair, Purdue University

Model theory of metric lattices

We propose a general first-order framework for studying geometric lattices within the model theory of metric structures. As an application we develop a novel continuous limiting theory for finite partition lattices and discuss potential implications to their asymptotic combinatorics. This is joint work with Jose Contreras-Mantilla.

QNC 1507 or Join on Zoom

Shintaro Fushida-Hardy, University of Waterloo

Constructing Lagrangians in S2xS2

We investigate the existence of non-orientable Lagrangian surfaces in symplectic S^2xS^2s. On one hand, it is known that a Klein bottle embedded in S^2xS^2 cannot be Lagrangian in almost half of the possible symplectic structures on S^2xS^2. On the other hand, we use trisection-inspired methods to describe a general construction of Lagrangian surfaces, and ask "what is the minimal genus such that a non-orientable Lagrangian surface of said genus exists in every symplectic S^2xS^2?". This is joint work with Laura Wakelin.

MC 5417

It is with sadness that we announce our William Gilbert passed away, surrounded by the love of his family on Saturday, October 25th, 2025 at the age of 84 years.  Will was a faculty member in our department for many years, retiring in 2004, and has been a fixture at various department events since then.  Those of you who knew him will remember his wry sense of humour and his cheerful demeanour.

Born in Exeter, England in March 1941, Will's early years took him from the Devon countryside to Deep River, Ontario—where his father Charles Gilbert was the lead Nuclear Physicist at Canada's first nuclear reactor—before the family returned to England and settled in Manchester. Will completed his undergraduate and master's degrees in mathematics at Cambridge University, and to his father's disappointment, completed his PhD at Oxford University. A distinguished mathematician and dedicated educator, Will built a remarkable academic career spanning nearly four decades at the University of Waterloo. He joined the Department of Pure Mathematics as an Assistant Professor in 1968, rising to full Professor and serving as Department Chair from 1995 to 1999 before becoming Professor Emeritus in 2004.

Will’s scholarly contributions were significant and diverse, exploring the elegant interplay between algebra and geometry. His research encompassed fractal geometry, complex bases, dynamical systems, and algebraic topology. He authored several influential textbooks, including "An Introduction to Mathematical Thinking" and "Modern Algebra with Applications," shaping the minds of countless mathematics students. He has 54 publications to his name, and his research is cited over 800 times according to ResearchGate. Throughout his career, he contributed to the study of mathematics internationally through research and teaching sabbaticals in Australia, New Zealand, and China

Beyond the classroom and research lab, Will embraced life as a quiet, patient, and caring man. He was known for his gentle presence, warm smile, and wry sense of humour. Will had a lifelong love of British comedy, particularly Monty Python—several members of which were his contemporaries at Cambridge and Oxford. He was an avid sailor, enjoying his Laser and Albacore sailboats on Conestoga Lake. He was a dedicated skier, enjoyed camping adventures, travelled the world extensively, and cultivated a refined palate as a wine connoisseur and member of both the International Cellar Society and the Kitchener German Wine Society. He once owned an extensive wine collection that was the envy of many. A passionate film enthusiast with a particular love for world cinema, he contributed reviews to the Internet Movie Database and attended the Toronto International Film Festival faithfully for decades.

In later years, Will treasured time with his family, completing jigsaw puzzles and swimming. His grandchildren adored their Grandpa deeply and will forever hold close memories of his kindness, intelligence, patience, and the special bond they shared.

Husband of Ruth Gilbert (née Hornig) for over 57 years. Loving father of Mandy Jean Ramirez (Jesse) and Peter Jay Gilbert (Farida). Cherished grandfather of Zachary Ramirez, Ethan Gilbert, and Gavin Gilbert. Dear big brother of Harry Gilbert (Awn) of England and Eva Smart of Australia. Loving uncle of Holly Gilbert, Judith Smart, Jonathan Smart, and Jason Smart.

Predeceased by his parents, nuclear physicist Charles Walton Gilbert and Irene Gilbert (née Gunn)

Cremation has taken place. A Celebration of Life open house will be held Sunday November 16th in the afternoon. Please email willcelebrationoflife@gmail.com for more information and to RSVP.

In lieu of flowers, donations may be made to Heart and Stroke Foundation of Canada as expressions of sympathy. Messages and condolences may be left at www.tricitycremations.com or 519.772.1237

Yunqing Tang, Berkeley

Irrationality of periods

Periods are interesting numbers arising from algebraic geometry. Grothendieck’s period conjecture provides predictions on irrationality and transcendence of periods. There have been some systematic studies on certain periods, such as Baker’s theory on linear forms of logarithms of algebraic numbers. However, beyond special cases, we do not know the irrationality of simple-looking periods such as the product of two logs. In this talk, I will discuss the joint work with Calegari and Dimitrov on an irrationality result of certain product of two logs and some other periods. A classical prototype of the method was first used by Apéry to prove the irrationality of zeta(3). The key ingredient is an arithmetic holonomy theorem built upon earlier work by André, Bost, Charles (and others) on arithmetic algebraization theorems via Arakelov theory.

MC 5501