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Wednesday, February 26, 2025 3:30 pm - 5:00 pm EST (GMT -05:00)

Differential Geometry Working Seminar

Facundo Camano, University of Waterloo

Bows to Singular Monopoles

We will discuss an approach to constructing singular monopoles on R^3 by Sergey Cherkis. We begin with the background and the traditional approach to constructing singular monopoles via the Nahm equations. We then talk about bows and their representations, along with the resulting moduli spaces and their self-dual instantons. We apply the bow approach to construct self-dual instantons on the multi-Taub-NUT space and then exploit Kronheimer's correspondence to obtain singular monopoles.

MC 5479

Thursday, February 27, 2025 4:00 pm - 5:00 pm EST (GMT -05:00)

Analysis Seminar

Pavlos Kalantzopoulos, UC Irvine

Analysis Seminar: A multiversion of real and complex hypercontractivity

We establish a multiversion of real and complex Gaussian hypercontractivity. More precisely, our result generalizes Nelson’s hypercontractivity in the real setting and the works of Beckner, Weissler, Janson, and Epperson in the complex setting to several functions. The proof relies on heat semigroup methods, where we construct an interpolation map that connects the inequality at the endpoints. As a consequence, we derive sharp multidimensional versions of the Hausdorff-Young inequality, a Noisy Gaussian-Jensen inequality, and the log-Sobolev inequality. This is joint work with Paata Ivanisvili.

MC 5417 or Join on Zoom

Tuesday, February 25, 2025 2:00 pm - 3:00 pm EST (GMT -05:00)

Logic Seminar

Clement Yung, University of Toronto

Weak A2 spaces, the Kastanas game and strategically Ramsey sets

In the past century, the insight behind the original Ramsey's theorem proved to be applicable to a wide range of mathematics, such as number theory, functional analysis and topology. This spurred two particular directions of Ramsey theory: The first one is known as topological Ramsey theory, a general procedure developed by Todorcevic to prove many seemingly unrelated Ramsey's theorem-like results. The second one is the Ramsey theory of Banach spaces, kickstarted by Gowers' shocking application of Ramsey theory to resolve a long-standing open problem in Banach space theory. In this talk, I introduce the theory of weak A2 spaces, which serves as a possible intersection between these two Ramsey theories and discuss how several infinite games that appeared in these Ramsey theories (the Kastanas game, the Gowers game and the asymptotic game) are closely related.

MC 5479

Monday, March 10, 2025 2:30 pm - 3:30 pm EDT (GMT -04:00)

Pure Math Department Colloquium

Elisabeth Werner, Case Western Reserve University

Affine invariants in convex geometry

In analogy to the classical surface area, a notion of affine surface area (invariant under affine transformations) has been defined. The isoperimetric inequality states that the usual surface area is minimized for a ball. Affine isoperimetric inequality states that affine surface area is maximized for ellipsoids. Due to this inequality and its many other remarkable properties, the affine surface area finds applications in many areas of mathematics and applied mathematics. This has led to intense research in recent years and numerous new directions have been developed. We will discuss some of them and we will show how affine surface area is related to a geometric object, that is interesting in its own right, the floating body.

MC 5501

Tuesday, February 25, 2025 10:00 am - 10:50 am EST (GMT -05:00)

Number Theory Seminar

Miao Gu, University of Michigan

On Triple Product L-functions

The Poisson summation conjecture of Braverman-Kazhdan, Lafforgue, Ngo and Sakellaridis is an ambitious proposal to prove analytic properties of quite general Langlands L-functions using vast generalizations of the Poisson summation formula. In this talk, we present the construction of a generalized Whittaker induction such that the associated L-function is the product of the triple product L-function and L-functions whose analytic properties are understood. We then formulate an extension of the Poisson summation conjecture and prove that it implies the expected analytic properties of triple product L-functions. Finally, we use the fiber bundle method to reduce this extended Poisson summation conjecture to a case of the Poisson summation conjecture in which spectral methods can be employed together with certain local compatibility statements. This is joint work with Jayce Getz, Chun-Hsien Hsu, and Spencer Leslie.

MC 5479

Thursday, February 20, 2025 4:00 pm - 5:00 pm EST (GMT -05:00)

Analysis Seminar

Becky Armstrong, Victoria University of Wellington

Analysis Seminar: Twisted groupoids that are not induced by continuous 2-cocycles

Twisted groupoids are generalisations of group extensions that play an important role in C*-algebraic theory: every classifiable C*-algebra has an underlying twisted groupoid model. It is well known that group extensions are in one-to-one correspondence with group 2-cocycles. Analogously, every groupoid 2-cocycle gives rise to a twisted groupoid. However, an example due to Kumjian shows that the converse is not true. Kumjian’s counterexample is a twisted groupoid consisting entirely of isotropy, but in this talk I will present a new example of a twisted groupoid that is not all isotropy, such that the twisted isotropy subgroupoid is not induced by a 2-cocycle. (This is joint work with Abraham C.S. Ng, Aidan Sims, and Yumiao Zhou.)

MC 5417

Monday, February 17, 2025 4:00 pm - 4:30 pm EST (GMT -05:00)

Mirror Symmetry Seminar

Kaleb D Ruscitti, University of Waterloo

Yukawa Coupling & the Mirror Map

The mirror map is a choice of co-ordinates on the moduli space of complex deformations Def(X) that come from natural co-ordinates on a moduli space of Kahler structures for X. In this presentation, we aim to introduce this map & the associated Yukawa couplings, in as much detail as possible given only one hour.

MC 2017

Tuesday, February 11, 2025 1:00 pm - 2:00 pm EST (GMT -05:00)

Algebraic Geometry Working Seminar

Jiahui Huang, University of Waterloo

Deformation of Complex Structures in Mirror Symmetry

In the spirit of relating the complex geometry of a Calabi-Yau manifold to the Kahler geometry of its mirror, this talk considers how their deformations relate to each other. We study deformations of complex structures via Kodaira-Spencer theory and Kahler structures via Gromov-Witten invariants. We will also look at how they relate to homological mirror symmetry.

MC 5479

Friday, February 14, 2025 5:30 pm - 6:30 pm EST (GMT -05:00)

Graduate Student Colloquium

Sourabh Das, University of Waterloo

Love, Life, and the Math Behind It -  Solving the Ultimate Equation

Finding love isn’t just about fate, chemistry, or the right swipe – it’s a problem. And if

there’s one thing math is great at, it’s solving problems (well, most of them). In this talk,

we’ll tackle the big questions of love using probability, and a touch of game theory:

- What are the odds of finding "The One"? (Spoiler: Finding aliens is actually more

likely.)

- When should you stop searching and settle down? (Mathematically, not emotionally.)

- How happy are you in your relationship? (A mathematical approach to the age-old

question: "Do they really know me?")

The first two parts will involve some surprisingly useful math to help you navigate the

dating world and optimize your love life. The final segment? A game designed to test your

compatibility with a "partner" – a friend, a crush, or your long-term love. To maximize

enjoyment (and potential awkwardness), attending in pairs is highly encouraged. In other

words: Bring a date. Or, if you’re feeling adventurous, let the math do the matchmaking!

MC 5417

(snacks at 5:00pm)

Friday, February 14, 2025 11:30 am - 12:30 pm EST (GMT -05:00)

Model Theory Working Seminar

Nicolas Chavarria Gomez, Waterloo

Curve Excluding Fields V

We continue reading through Will Johnson's and Vincent Ye's paper on the theory of existentially closed fields excluding a curve.

MC 5403