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27 Transformation Groups Seminar
Transformation Groups Seminar Speaker: Larry So (Western) "The quotient construction and homogeneous coordinates of toric varieties" Time: 10:30 - 11:30 Room: MC 108 Algebraic Geometry
Algebraic Geometry Speaker: Kate Kim (Western) "WAG: 0-dimensional ideals" Time: 15:30 - 16:30 Room: MC 108 |
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1 Graduate Seminar
Graduate Seminar Speaker: Marwa Tuffaha (Western) "Mutator dynamics cannot be explained by mutation rates alone" Time: 16:30 - 17:30 Room: MC 107 Mutators, cells with elevated mutation rates, are common in both natural microbial populations and in human cancers. Recent experiments have shown that mutators can invade a population, but the invasion dynamics and probability couldn’t be explained by mutation rates alone. Here we show, analytically and in simulation, that mutation bias (which types of mutations are likely to occur) can play an important role in the emergence of mutators. A mutator that reduces or reverses the historically prevailing mutational bias is shown to have an increased chance of invasion, while chances are reduced when the bias is reinforced. These findings are important when trying to understand natural populations or competition experiments with mutators. |
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5 Transformation Groups Seminar
Transformation Groups Seminar Speaker: (Western) "Polytopes and Toric Varieties" Time: 10:30 - 11:30 Room: MC 204 Algebraic Geometry
Algebraic Geometry Speaker: Michael Francis (Western) "WAG: Primary Decomposition" Time: 15:30 - 16:30 Room: MC 107 |
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7 Department Meeting
Department Meeting Speaker: "Department Meeting" Time: 15:30 - 16:30 Room: TBA |
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12 Transformation Groups Seminar
Transformation Groups Seminar Speaker: Sayantan Roy Chowdhury (Western) "Toric regularity (cancelled)" Time: 10:30 - 11:30 Room: MC 204 Algebraic Geometry
Algebraic Geometry Speaker: Greg Reid (Western) "WAG: Linear PDE's with constant coefficients" Time: 15:30 - 16:30 Room: MC 107 Colloquium
Colloquium Speaker: George Shillcock (University of Oxford) "Evolution Theory Talk - Division of labour" Time: 15:40 - 16:40 Room: MC 204 A collective evolves division of labour when its members all benefit by specialising to perform complementary tasks. It is observed across various scales of biological organisation at the origins of multicellularity and eusociality. It is, therefore, of interest to understand the conditions which favour the evolution of division of labour by natural selection. By focusing our attention to collectives that reproduce clonally, such as many plants and bacteria, we may safely model collectives as fitness maximisers faced with a constrained optimisation. |
13 Geometry and Topology
Geometry and Topology Speaker: Steven Amelotte (Western) "Homotopy types of moment-angle complexes and minimal free resolutions of Stanley-Reisner rings" Time: 15:30 - 14:30 Room: MC 107 Toric topology assigns to each finite simplicial complex K a space with a torus action, called the moment-angle complex, whose equivariant topology neatly reflects combinatorial properties of K and homological properties of the Stanley-Reisner ring of K. A central result in the subject identifies the cohomology of the moment-angle complex with the Koszul homology of the corresponding Stanley-Reisner ring. In this talk, I'll describe how cohomology operations induced by the torus action can be used to extend this result to a topological interpretation of the entire minimal free resolution of the Stanley-Reisner ring, and then outline some work in progress which aims to identify the homotopy types of certain moment-angle complexes in terms of this data.
(This is all based on joint work with Ben Briggs.) Pizza Seminar
Pizza Seminar Speaker: Lindi Wahl (Western) "Generating predictions: the power and elegance of generating functions." Time: 17:00 - 18:30 Room: MC 107 Like other transform methods, generating functions sometimes offer a lens through which an otherwise complicated problem has a surprisingly elegant solution. I'll offer a quick introduction to probability generating functions and show how we can take advantage of some really beautiful theorems to make practical predictions -- like the probability that COVID-19 has driven the Yamagata flu strain to extinction. |
14 Ph.D. Presentation
Ph.D. Presentation Speaker: Third-year Ph.D. students (Western) "TBA" Time: 15:30 - 17:00 Room: MC 107 |
15 Graduate Seminar
Graduate Seminar Speaker: Thomas Thorbjornsen (Western) "The Synthetic Fundamental Group of the Circle" Time: 16:30 - 17:30 Room: MC 107 Homotopy type theory is a foundation for mathematics that is well-suited to do homotopy theory. Unlike ZFC, we no longer have access to the law of excluded middle or the axiom of choice. Many mathematicians find it daunting and off-putting to work without these axioms, but great opportunity is created amidst the challenge. In this talk we will investigate how we can do homotopy theory in homotopy type theory. We will construct the fundamental group of the circle by using the tools provided by Martin-Löf type theory, Voevodsky’s univalence axiom, and higher inductive types. In particular, we will look at the underlying language of type theory and its identity types, how fiber bundles are expressed as type families, and the essential role played by the univalence axiom. |
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Transformation Groups Seminar
Transformation Groups Seminar Speaker: Sayantan Roy Chowdhury (Western) "Toric regularity" Time: 10:30 - 11:30 Room: MC 204 Algebraic Geometry
Algebraic Geometry Speaker: Meagan James (Western) "WAG: Elimination" Time: 15:30 - 16:30 Room: MC 107 |
Geometry and Topology
Geometry and Topology Speaker: Rasul Shafikov (Western) "Special embeddings in complex analysis" Time: 15:30 - 16:30 Room: MC 107 Since Whitney's classical result of smooth embedding of manifolds into $\mathbb R^n$, one of the themes in geometry has been the existence of embeddings that preserve additional structure, for example, isometric embeddings of Riemannian manifolds or embeddings as symplectic or isotropic submanifolds into euclidean spaces with the standard Riemannian or symplectic structure. In this talk I will discuss some old and new problems concerning embeddings with special properties of complex or real manifolds into complex Euclidean spaces. We start with Stein manifolds and then discuss totally real embeddings and embeddings with special approximation properties. These problems have a topological component, such as Gromov's h-principle and Morse theory. |
Colloquium
Colloquium Speaker: Cristian Bravo Roman (Western) "Are causal effects estimations the key to optimal recommendations under multi-treatment scenarios?" Time: 15:30 - 16:30 Room: MC 108 Abstract: When making decisions that impact a specific context, it is essential to include a causal effect estimation analysis. This analysis allows us to compare potential outcomes under different treatment options or the control, aiding in selecting the best treatment option that leads to optimal results. However, merely estimating individual treatment effects may not suffice for making truly optimal decisions. To reveal this limitation, our study explores the incorporation of additional criteria, such as the uncertainty of these estimations, measured through a concept similar to the Conditional Value-at-Risk, commonly used in portfolio and insurance management. Additionally, we evaluate the inclusion of a specific prediction condition, particularly when the highest output is the desired outcome. With these intentions in mind, we propose a comprehensive methodology for multi-treatment selection, especially in situations where greater output is more desirable. Our suggested approach ensures the satisfaction of the overlap condition for comparing outcomes for treated and control groups. This involves training propensity score models as a preliminary step before employing traditional causal models — a crucial aspect often overlooked in other research. To illustrate the practical application of our methodology, we focus on the significant problem of credit card limit adjustment, which has historically been reliant on expert-driven choices. Analyzing historical data from a fintech company, we discovered that relying solely on counterfactual predictions is inadequate for generating appropriate credit line modifications. Instead, incorporating the two additional criteria significantly enhances the performance of the generated policy. Short bio: Dr. Cristián Bravo is an Associate Professor and Canada Research Chair in Banking and Insurance Analytics at Western University, and Director of the Banking Analytics Lab. His research focuses on data science, analytics, and credit risk, particularly exploring multimodal deep learning, causal inference, and social network analysis to understand consumer-financial institution relations. With over 75 publications in prestigious journals and conferences, he contributes significantly to operational research, finance, and computer science. He frequently appears on CBC News’ Weekend Business Panel, and has been quoted by The Wall Street Journal, WIRED, CTV, The Toronto Star, The Globe and Mail, and Global News discussing topics in Banking, Finance, and Artificial Intelligence. |
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Colloquium
Colloquium Speaker: Matthew Davison (Western) "TBA" Time: 15:30 - 16:30 Room: MC 108 |
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Algebraic Geometry
Algebraic Geometry Speaker: Curtis Wilson (Western) "WAG: The image of a polynomial map" Time: 15:30 - 16:30 Room: MC 107 |
Geometry and Topology
Geometry and Topology Speaker: Luuk Stehouwer (Western) "TBD" Time: 15:30 - 16:30 Room: MC 108 |
Colloquium
Colloquium Speaker: Ajneet Dhillon (Western) "Basic Notions: TBD" Time: 15:30 - 16:30 Room: MC 108 |
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