Discrete math seminar - University of Victoria

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3562 PIMS Network-wide Colloquium: Title TBA Please <a href="https://ubc.zoom.us/meeting/register/OoGJFra5SMiLY8pSQJqhJw#/registration">register here</a>. via Zoom registration required 2026-03-26 13:30:00 14:30:00 PIMS lectures Melanie Wood Harvard University 3561 PIMS Network-wide Colloquium: Title TBA Please <a href="https://ubc.zoom.us/meeting/register/OoGJFra5SMiLY8pSQJqhJw#/registration">register here</a>. via Zoom registration required 2026-02-12 13:30:00 14:30:00 PIMS lectures Helen Byrne University of Oxford 3560 PIMS Network-wide Colloquium: Title TBA Please <a href="https://ubc.zoom.us/meeting/register/OoGJFra5SMiLY8pSQJqhJw#/registration">register here</a>. via Zoom registration required 2026-01-22 13:30:00 14:30:00 PIMS lectures Vinod Vaikuntanathan MIT 3552 Maud Menten Lecture: TBD CLE A317 and Zoom 2025-12-08 12:00:00 13:00:00 Math biology seminar James Watmough University of New Brunswick 3582 PIMS-UVic Women in Math Lecture Series Unlikely intersections from iterations: the riddle of shared preperiodic points From Babylonian root-finding algorithms to Fatou-Julia's WW1 era fractals, iteration has always led to hidden patterns. But when do dynamical systems share many preperiodic points - numbers trapped in finite loops? We'll explore this theme of unlikely intersections connected to the notion of preperiodic points. Light refreshments will be provided DSB C118 2025-12-02 15:30:00 16:20:00 PIMS lectures Niki Myrto Mavraki University oif Toronto Mississauga 3556 Gambling for resurrection: environmental fluctuations can reduce extinction risk for highly at-risk populations Random fluctuations in environmental conditions (environmental stochasticity) are thought to increase population extinction risk. But as gamblers, politicians, and sports teams know, even bad risks become good risks when you are facing imminent defeat ("gambling for resurrection"). Analogously, populations at high risk of imminent extinction can benefit from environmental fluctuations that create some chance of long-term persistence. I will illustrate this principle with mathematical models, an experiment with Daphnia, and analogies to poker, hockey, and the movie Wag the Dog. CLE A317 and Zoom 2025-12-01 12:00:00 13:00:00 Math biology seminar Jeremy Fox University of Calgary 3583 Numerical Construction of K-Optimal Designs for Linear, Nonlinear, and Generalized Linear Models Notice of the Final Oral Examination for the Degree of Master of Science of XIAOQING (RENA) ZHANG BSc (University of Victoria, 2020) “Numerical Construction of K-Optimal Designs for Linear, Nonlinear, and Generalized Linear Models” Department of Mathematics and Statistics Friday, November 28, 2025 2:00 P.M. Virtual Defence Supervisory Committee: Dr. Julie Zhou, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Min Tsao, Department of Mathematics and Statistics, UVic (Member) External Examiner: Dr. Po Yang, Department of Statistics, University of Manitoba Chair of Oral Examination: Dr. Daler Rakhmatov, Department of Electrical and Computer Engineering, UVic Abstract This thesis investigates the numerical construction of K-optimal designs for a variety of statistical models. These include linear models such as polynomial, trigonometric, and second-order response models, nonlinear models such as Michaelis–Menten, compartmental, and Peleg models, and generalized linear models with a particular focus on logistic regression. K-optimality aims to minimize the condition number of the Fisher information matrix to improve the numerical stability in parameter estimation. A general algorithm is proposed and applied to all models to construct K-optimal designs, evaluated under different design spaces and parameter values. For nonlinear models, the K-optimal designs are compared with A-optimal and D-optimal designs, while for the logistic regression model, comparisons are made with D-optimal designs. The results show that K-optimal designs have stable patterns between different models. Factors such as design space, model type, and parameter values influence the support points, their weights, and the condition number. In addition, K-optimal designs achieve smaller condition numbers, indicating better numerical stability, and take less computation time than both D-optimal and A-optimal designs. All key findings are presented in tables and figures, and the MATLAB code used for the computations is provided in the thesis. via Zoom 2025-11-28 14:00:00 15:00:00 Graduate dissertations Xiaoqing (Rena) Zhang University of Victoria 3543 Quaternary Legendre Pairs Abstract: In this talk we will address the relatively new objects quaternary Legendre pairs. These objects (and their binary counterparts) were introduced in order to construct Hadamard matrices and have garnered renewed interest recently. Over the course of this talk, it will be shown that quaternary Legendre pairs of even length are the “interesting” examples, and we will present the first known constructions of these sequences. In addition, a brief survey of Legendre pairs and related techniques in the constructions of Hadamard matrices will be covered. MAC D101 2025-11-27 10:00:00 11:00:00 Discrete math seminar Thomas Pender Simon Fraser University 3581 On certain Hecke algebras arising as deformations of group algebras of Coxeter groups Abstract: Operator algebras associated with discrete groups have played a significant role in the theory of operator algebras since its inception over 80 years ago. I will recall fundamental questions related to this class and present certain operator algebras which can be viewed as deformations of algebras of (right-angled) Coxeter groups: the so-called q-Hecke operator algebras. We shall see how the algebras in question arise in various natural ways, in particular related to groups acting on buildings, and then characterise some of their properties in terms of the deformation parameters (based on joint work with Sven Raum). CLE D134 2025-11-26 15:30:00 16:45:00 Operator theory seminar Adam Skalski IMPAN 3580 Cooperative motion in higher dimensions Abstract: Cooperative motion is a random walk process where the jump rate of a particle depends on the likelihood that another independent identical walker is at the same position. It was studied on the line in a paper by Addario-Berry, Cairns, Devroye, Kerriou and Mitchell and two papers by Addario-Berry, Beckman, and Lin. We find the scaling limit for lattices $Z^d, d \ge 1$ in the special case of simple symmetric walk. This is the first result in dimension greater than one. via Zoom 2025-11-25 14:30:00 15:30:00 Probability and Dynamics seminar Hannah Cairns McGill University 3555 On reinforced random walks with bees: An analysis of how traplines form Traplining is a behaviour widely observed across many species, where animals repeatedly undertake foraging excursions called bouts, adjusting the sequence in which they visit food sources as they gain more experience, eventually repeating the same route consistently. This repeated route is known as a trapline. An intriguing biologically plausible model for trapline formation in bees was proposed by Lihoreau et al. in 2012. Using theory related to reinforced random walks, we examine the long-term behaviour of these models. We test hypotheses about how traplines form by directly fitting reinforced random walk models to bumblebee foraging data. This novel approach to studying animal learning uncovers new insights into the behavioural signatures of bumblebee foraging. CLE A317 and Zoom 2025-11-24 12:00:00 13:00:00 Math biology seminar Ferdinand Gruenenwald University of Victoria 3559 PIMS Network-wide Colloquium: Tree decompositions: representing a graph by a tree Please <a href="https://ubc.zoom.us/meeting/register/OoGJFra5SMiLY8pSQJqhJw#/registration">register here</a>. How does one describe the structure of a graph? What is a good way to measure how complicated a given graph is? Tree decompositions are a powerful tool in structural graph theory, designed to address these questions. To obtain a tree decomposition of a graph G, we break G into parts that interact with each other in a simple ("tree-like") manner. But what properties do the parts need to have in order for the decomposition to be meaningful? Traditionally a parameter called the "width" of a decomposition was considered, that is simply the maximum size of a part. In recent years other ways of measuring the complexity of tree decompositions have been proposed, and their properties are being studied. In this talk we will discuss recent progress in this area, touching on the classical notion of bounded tree-width, concepts of more structural flavor, and the interactions between them. Additional Information Maria Chudnovsky is a prominent mathematician known for her work in graph theory and combinatorics. Her work on the proof of the strong perfect graph theorem won for her and her co-authors the 2009 Fulkerson Prize. She earned her degrees from the Technion and Princeton University, and holds a position at Princeton University, having previously taught at Columbia University. A recipient of a 2012 MacArthur Fellowship, her research focuses on the structure of graphs and has real-world applications in areas such as transportation and computer networks. via Zoom registration required 2025-11-20 13:30:00 14:30:00 PIMS lectures Maria Chudnovsky Princeton University 3541 Why do some harmonic analysts sound like us? In recent years, harmonic analysts and fractal geometers have become increasingly interested in Ramsey-theoretic problems for subsets of Rn. Many of these were inspired by discrete analogues. Over the past 20 years, classical theorems from discrete mathematics—including Roth’s 3-term arithmetic progression theorem, the Furstenberg–Sárközy theorem on perfect square differences, and the Salem–Spencer arithmetic-progression-free sets—have been successfully translated to the real-number setting. In the first half of this talk, I will highlight some of these Euclidean analogues and explain how they arose. In the second, I will discuss my recent work on a variant of an old problem of Erdős concerning the (non-)existence of sequences inside “large” sets. The talk assumes minimal background. You may find familiarity with Lebesgue measure useful, but it’s enough to think of it as length. No fractal geometry experience is required. MAC D101 2025-11-20 10:00:00 11:00:00 Discrete math seminar Yuveshen Mooroogen University of British Columbia 3579 The largest common subtree of two random trees Abstract - Given two trees, what is the size and structure of their largest common shared subtree? This question has been a growing topic of interest in the probability/combinatorics community in recent years, with the problem having been discussed for a few different models of random trees. In this talk, we will discuss the case where the two trees are independent Bienaymé-Galton-Watson trees with finite-variance offspring distributions, conditioned to have size n. The main result will be a scaling limit for the size of the largest common subtrees of two such Bienaymé trees under some light assumptions. The talk is based on joint work with Omer Angel, Anna Brandenberger, Serte Donderwinkel, and Robin Khanfir. via Zoom 2025-11-18 14:30:00 15:30:00 Probability and Dynamics seminar Caelan Atamanchuk McGill University 3554 SPaCeD: Spatial Point Process Distances for Pairing the Heavy and Light Chains of B Cell Receptors from Spatial BCR-seq The immune system identifies and mounts a defense against tumor cells through antigen recognition, a process mediated primarily by T cells and B cells. B cells are equipped with heavy and light receptor chains, whereas T cells carry alpha and beta receptor chains. These receptors recognize antigens and orchestrate an immune response, making their accurate pairing essential for understanding tumor-immune interactions. We develop an approach based on spatial BCR-seq to infer receptor chain pairings. Our approach is formulated as a combinatorial optimization problem with an objective function that incorporates the expression matrices of heavy and light chains with their spatial co-expression point patterns derived from barcoded pixels. Spatial information is represented as distances between point patterns computed using an optimal transport algorithm. The estimated receptor heavy and light chain pairs have potential application in the development of targeted immunotherapies. The methodology is evaluated using nine simulation studies based on ovarian and breast cancer samples, as well as with real data where the ground truth is known from single-cell sequencing. Substantial improvements in terms of both accuracy and stability are demonstrated over existing state-of-the-art. CLE A317 and Zoom 2025-11-17 12:00:00 13:00:00 Math biology seminar Flora Liu University of Victoria 3578 Playing Sudoku on random 3-regular graphs Abstract: The \textit{Sudoku} number $s(G)$ of graph $G$ with chromatic number $\chi(G)$ is the smallest partial $\chi(G)$-colouring of $G$ that determines a unique $\chi(G)$-colouring of the entire graph. We show that the Sudoku number of the random $3$-regular graph $\mathcal{G}_{n,3}$ satisfies $s(\mathcal{G}_{n,3}) \leq (1+o(1))\frac{n}{3}$ asymptotically almost surely. We prove this by analyzing an algorithm which $3$-colours $\mathcal{G}_{n,3}$ in a way that produces many \textit{locally forced} vertices, i.e., vertices which see two distinct colours among their neighbours. The intricacies of the algorithm present some challenges for the analysis, and to overcome these we use a non-standard application of Wormald's \textit{differential equations method} that incorporates tools from finite Markov chains. 2025-11-17 10:30:00 11:30:00 Discrete math seminar Pawel Pralat Toronto Metropolitan University 3576 Advancing Cell-Type Annotation and Deconvolution in Human Bronchoalveolar Lavage Through Single-Cell Transcriptomics and Benchmarking Protocols Examining Committee Supervisory Committee Dr. Xuekui Zhang, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Xiaojian Shao, Department of Mathematics and Statistics, UVic (Co-Supervisor) Dr. Belaid Moa, Department of Electrical and Computer Engineering, UVic (Outside Member) External Examiner Dr. Pingzhao Hu, Department of Biochemistry, Western University Chair of Oral Examination Dr. Shengyao Lu, Department of Computer Science, UVic Abstract Bronchoalveolar lavage (BAL) provides a unique view to analyze immunological aspects of the human lung. single-cell RNA sequencing data (scRNA-seq) of BAL offers a great potential for immunotherapy of lung diseases. Despite promising, challenges persist in identifying disease-relevant high-resolution subcell types, standardizing annotations across studies, and accurately interpreting bulk RNA-seq data. This dissertation is approached from three perspectives. Chapter one serves as the introduction, while chapter two provides the background. Chapter three presents scRNA-seq data utilized to characterize macrophage and monocyte populations in chronic obstructive pulmonary disease (COPD). The analysis identified dysfunctional alveolar macrophages and hyperinflammatory monocytes, indicating potential therapeutic targets and emphasizing the modulatory effects of inhaled corticosteroids. The fourth chapter presents a standardized atlas of human BAL cells through the synthesis multiple scRNA-seq datasets, with ensemble auto-annotation tools and reliable cross-study markers. This atlas deals with discrepancies in previous studies and provides a foundation for BAL research. Chapter five introduces the first true-paired benchmarking study of cellular deconvolution in BAL. Including 30 human BAL samples, each divided into bulk RNA-seq and matched single-cell libraries. After systematically evaluating 15 popular algorithms across multiple references and cell-type resolutions, this study demonstrates a modestly designed pairing strategy substantially improves both benchmark realism and practical accuracy. Our true-paired data, comparative analyses, and three-step protocol provide a blueprint for future deconvolution studies. Together, these chapters deliver disease insights, community resources, and methodological frameworks that advance the study of lung immunity through both single-cell and bulk transcriptomics. 2025-11-12 08:00:00 09:00:00 Graduate dissertations Yushan Hu University of Victoria 3577 Lipschitz functions on weak expanders Abstract: Given a connected finite graph $G$, an integer-valued function $f$ on $V(G)$ is called $M$-Lipschitz if the value of $f$ changes by at most $M$ along the edges of $G$. In 2013, Peled, Samotij, and Yehudayoff showed that random $M$-Lipschitz functions on graphs with sufficiently good expansion typically exhibit small fluctuations, giving sharp bounds on the typical range of such functions, assuming $M$ is not too large. We prove that the same conclusion holds under a relaxed expansion condition and for larger $M$, (partially) answering questions of Peled et al. Our approach combines Sapozhenko’s graph container method with entropy techniques from information theory. This is joint work with Krueger and Park. via Zoom 2025-11-11 14:30:00 15:20:00 Probability and Dynamics seminar Lina Li University of Mississippi 3542 On the second largest eigenvalue of certain graphs in the perfect matching association scheme Defined as the difference between its two largest eigenvalues, the spectral gap of a graph plays an important role on our understanding of its connectivity as observed by Godsil and Royle (2001). Since computing the largest eigenvalue of a graph is generally not too difficult, the crux to understanding the spectral gap of a graph is to compute its second largest eigenvalue. In this talk, we will consider the spectral gap of certain graphs in the perfect matching association scheme. Since these graphs are part of the same association scheme, they have the same eigenspaces. These eigenspaces correspond to certain irreducible representations of the symmetric group and thus, one could use these irreducible representations to compute the eigenvalues of each graph. In practice, such computations are difficult to perform which makes it difficult to find the eigenspace that realizes the second largest eigenvalue. The focus of my talk will be to identify this eigenspace for selected graphs in the scheme. This is joint work with Himanshu Gupta, Allen Herman, Roghayeh (Mitra) Maleki, and Karen Meagher. MAC D101 2025-11-06 10:00:00 11:00:00 Discrete math seminar Alice Lacaze-Masmonteil University of Regina 3575 Lifting KK-duality to rational solenoids (Part 2 of 2) Abstract: Cuntz-Pimsner algebras form a broad class of C*-algebras generalizing both crossed products by Z and graph algebras. In their 2019 paper, Rennie, Robertson and Sims showed how one can establish KK-duality between a pair of Cuntz-Pimsner algebras by using a lift of the duality classes between their coefficient algebras, though constructing a cycle for this lift remains a challenge. I will give a solution to this problem for rational solenoids, showing how the Dirac operator on the circle can be lifted to a spectral triple that implements Poincaré duality between a pair of C*-algebras O(m/n) and O(n/m). A key step is the construction of an unbounded cycle representing the Toeplitz-Pimsner extension class, which we do in the more general context of bi-Hilbert bimodules. CLE D134 2025-11-05 15:30:00 16:45:00 Operator theory seminar Tyler Schulz University of Victoria 3574 A unifying approach to the replica-symmetric regime in general dilute spin glasses In this talk, I shall present a unifying approach to study the replica-symmetric regime of general dilute spin glasses. In particular, we identify two regimes - high temperature and subcritical dilution - where we observe a large class of popular spin glasses exhibiting replica-symmetric behavior. We revisit several well-known formulas for the free and ground state energies of some of these models and derive new ones for some others. Joint work with Arnab Sen and Wei-Kuo Chen. MAC D107 2025-11-04 15:30:00 16:20:00 Probability and Dynamics seminar Ratul Biswas NITMB 3553 Maud Menten Lecture: Building new metrics for analyzing large biological shape data Recent advances in experimental methodologies and community efforts led to a surge in large and heterogeneous biological datasets across all scales, that require the developments of new methods to extract meaningful information. In this context, I will describe our recent efforts to leverage optimal transport theory with the introduction of new metrics and algorithms, to compare data points in high dimensional spaces with applications in structural, molecular, and cell biology. After motivating these methods and briefly introducing the concept of Wasserstein distance, I’ll introduce two new frameworks. To quantify heterogeneity arising from large collections of 2D or 3D cell shapes, we define the stratified Wasserstein kernel, which embeds shape data in Euclidean space via ranked local distance profiles. This embedding yields an isometry-invariant Euclidean distance and a positive-definite kernel for population analysis, with a consistent sample-based estimator that supports large datasets in nearquadratic time. By leveraging kernel methods, the framework enables statistically rigorous tasks such as nonparametric hypothesis testing, providing theoretical guarantees as well as interpretability. Second, to improve and automate the fitting of protein subunits into large complexes imaged from cryo-EM, we formulate a new objective function -called Joint Gromov Wasserstein (JGW)-, which extends the mathematical concepts underlying the Gromov-Wasserstein objective, such as metric measure spaces and isomorphisms, to handle collections of objects. We prove theoretical properties of the JGW objective, analyzing its metric properties and asymptotic behavior from point sampling, and adapt existing approximation techniques to produce feasible algorithms to compute it. CLE A317 and Zoom 2025-11-03 12:00:00 13:00:00 Math biology seminar Khanh Dao Duc University of British Columbia 3570 The Turán Density of Tight Cycles Abstract: I will discuss several recent results on the Turán density of long cycle-like hypergraphs. These results (due to Kamčev–Letzter–Pokrovskiy, Balogh–Luo, and myself) all follow a similar framework, and I will outline a general strategy to prove Turán-type results for tight cycles in larger uniformities or for other "cycle-like" hypergraphs. One key ingredient in this framework, which I hope to prove in full, is a hypergraph analogue of the statement that a graph has no odd closed walks if and only if it is bipartite. More precisely, for various classes C of "cycle-like" r-uniform hypergraphs — including, for any k, the family of tight cycles of length k modulo r — we equiivalently characterize C-hom-free hypergraphs as those admitting a certain type of coloring of (r-1)-tuples of vertices. This provides a common generalization of results due to Kamčev–Letzter–Pokrovskiy and Balogh–Luo. MAC D101 2025-10-30 10:00:00 11:00:00 Discrete math seminar Maya Sankar Institute for Advanced Studies 3571 Lifting KK-duality to rational solenoids Abstract: Cuntz-Pimsner algebras form a broad class of C*-algebras generalizing both crossed products by Z and graph algebras. In their 2019 paper, Rennie, Robertson and Sims showed how one can establish KK-duality between a pair of Cuntz-Pimsner algebras by using a lift of the duality classes between their coefficient algebras, though constructing a cycle for this lift remains a challenge. I will give a solution to this problem for rational solenoids, showing how the Dirac operator on the circle can be lifted to a spectral triple that implements Poincaré duality between a pair of C*-algebras O(m/n) and O(n/m). A key step is the construction of an unbounded cycle representing the Toeplitz-Pimsner extension class, which we do in the more general context of bi-Hilbert bimodules. CLE D134 2025-10-29 15:30:00 16:45:00 Operator theory seminar Tyler Schulz University of Victoria 3573 Phase transitions of graphical representations of the Ising model Abstract: Much of the recent rigorous progress on the classical Ising model was driven by new detailed understanding of its stochastic geometric representations. Motivated by the problem of establishing exponential decay of truncated correlations of the supercritical Ising model in any dimension,Duminil-Copin posed the question in 2016 of determining the (percolative) phase transition of the single random current. Using that the loop O(1) model is the uniform even graph of the random cluster model, we prove polynomial lower bounds for path probabilities (and infinite expectation of cluster sizes of 0) for both the single random current and loop O(1) model corresponding to any supercritical Ising model on the hypercubic lattice. The method partly extends to all positive integers q, where the analogue of the loop O(1) model is the q-flow model. In this talk, I will introduce graphical representations of the Potts and Ising model and their many couplings followed by a discussion of new results whose surprising proof takes inspiration from the toric code in quantum theory. Based on : <a href="https://link.springer.com/article/10.1007/s00220-025-05297-3">https://link.springer.com/article/10.1007/s00220-025-05297-3</a> and <a href="https://arxiv.org/abs/2506.10765">https://arxiv.org/abs/2506.10765</a> via Zoom 2025-10-28 14:30:00 15:30:00 Probability and Dynamics seminar Frederik R. Klausen Princeton 3572 Site percolation on planar graphs Abstract: Site percolation models are probability distributions of 2-colorings of the vertices of locally finite infinite graphs. Historically, they have been studied on graphs exhibiting symmetries such as (quasi)-transitivity. In joint work with Alexander Glazman and Matan Harel, we instead only assume that the graph is planar. We show that a large class of site percolation models on any planar graph contains either zero or infinitely many infinite connected components. This includes the case of Bernoulli percolation at parameter p \leq 1/2, resolving a conjecture from the work of Benjamini and Schramm from 1996. In this talk, I will discuss the main ingredients of the proof, with emphasis on the properties we require of the model. via Zoom 2025-10-28 10:30:00 11:30:00 Probability and Dynamics seminar Nathan Zelesko Northeastern 3551 Reassessing the Statistical Evidence in Clinical Trials with Extended Approximate Objective Bayes Factors CLE A317 and Zoom 2025-10-27 12:00:00 13:00:00 Math biology seminar Puneet Velidi University of Victoria 3540 Lagrangians, Palettes, and Uniform Turan Densities The Turan density of a forbidden hypergraph F is the largest edge density a large hypergraph H can have without containing any copy of F, and determining this number for various F is a notoriously difficult problem. One on-ramp to this question (from Erdos and Sos) is to furthermore require that the hyperedges of H are distributed nearly uniformly across the vertices, giving the uniform Turan density of F. All known examples of such uniformly dense H avoiding some F follow the so-called “palette” construction of Rodl. In this talk we will introduce each of these notions before discussing our main result, that any palette can be obtained as an extremal construction for some finite family of forbidden subgraph F, which will require the tools of hypergraph regularity and Lagrangians. As an application we can obtain some (interesting) new values as the uniform Turan density of forbidden families. Based on joint work with Simon Piga, Marcelo Sales, and Bjarne Schuelke. MAC D101 2025-10-23 10:00:00 11:00:00 Discrete math seminar Dylan King Caltech 3550 Can introduced parasitoids destabilize control of introduced winter moth? 43 years of data from Mt. Tolmie, Victoria. CLE A317 and Zoom 2025-10-20 12:00:00 13:00:00 Math biology seminar Jens Roland University of Alberta 3568 Gysin sequences for boundary actions (Part 3 of ?) Abstract: We explain how the Baum-Connes conjecture can be used to compute the K-theory of the crossed product C*-algebras obtained from actions of groups acting on `boundaries at infinity' in the form of an analogue of the Gysin sequence from algebraic topology. CLE D134 2025-10-15 15:30:00 16:45:00 Operator theory seminar Heath Emerson University of Victoria 3567 Topological glass-blowing Abstract: Join the Math and Stats department for a discussion of surface topology, mathematical art and knot theory. Cliﬀ Stoll is the author of several books, including the Cuckoo’s Egg, his story of his role in one of the ﬁrst internet-espionage cases. He appears on many Numberphile videos and has been creating ACME (glass) Klein Bottles for over two decades. Lucas Clarke is the Scientiﬁc Glass Blower at SFU, and is perhaps the only person to have made a glass Boy Surface. We anticipate an entertaining discussion and at least one glass sculpture ‘crowd prize’ (provided they do not break on Stoll’s ﬂight to Vancouver). ECS 123 2025-10-15 15:30:00 16:30:00 Colloquia Cliff Stoll and Lucas Clarke (SFU) 3569 Random Spanning Trees in Random Environment Abstract: We will introduce Random Spanning Trees in Random Environment (RSTRE), a disordered system on spanning trees that interpolates between the Uniform Spanning Tree (UST) and Minimum Spanning Tree (MST) measures. Our primary goal is to study how local and global observables of the RSTRE depend on the inverse temperature beta. Of particular interest is the diameter of a (typical) spanning tree, as it is the first step towards establishing convergence to a non-trivial scaling limit. Furthermore, for the RSTRE on the complete graph with uniform disorder, we discuss a sharp transition of the local limit of the RSTRE to either the UST or MST local limit. This stands in contrast to our conjectured smooth transition of the diameter when beta is inside the so-called intermediate regime. via Zoom 2025-10-14 10:30:00 11:30:00 Probability and Dynamics seminar Luca Michael Makowiec University of Leipzig 3539 The unstable dual of a 2-cell embedding Abstract: A 2-cell embedding of a graph G in an orientable surface of genus k is an embedding in which each face is homeomorphic to an open disk. The distribution of genus across all 2-cell embeddings of G is called the genus distribution of G. In this talk, we explore embeddings of cubic planar graphs, particularly those with small genus. Using local rotations, we explore ways of describing each embedding of a cubic planar graph and how the face structure differs from that of a planar embedding. We introduce the unstable dual of an embedding of a cubic planar graph, a subgraph of the dual graph, and show how the genus of the corresponding embedding can be determined from properties of this unstable dual. This is joint work with Bojan Mohar (Simon Fraser University and University of Ljubljana). MAC D101 2025-10-09 10:00:00 11:00:00 Discrete math seminar Mackenzie Carr Toronto Metropolitan University 3565 Gysin sequences for boundary actions (Part 2 of ?) Abstract: We explain how the Baum-Connes conjecture can be used to compute the K-theory of the crossed product C*-algebras obtained from actions of groups acting on `boundaries at infinity' in the form of an analogue of the Gysin sequence from algebraic topology. CLE D134 2025-10-08 15:30:00 16:45:00 Operator theory seminar Heath Emerson University of Victoria 3557 UVic Undergraduate Math Competition The 2025 UVic Math competition is scheduled for Tuesday, October 7, from 4:00pm to 6:00pm in HSD A264. No registration is required, but any questions can be directed to <a href="mailto:dukes@uvic.ca">dukes@uvic.ca</a>. Past contests are on the web page at <a href="https://web.uvic.ca/~dukes/other.html">https://web.uvic.ca/~dukes/other.html</a>. HSD A264 2025-10-07 16:00:00 18:00:00 Education and outreach 3566 Coverage and connectivity in stochastic geometry Abstract: Consider a random uniform sample of size $n$ over a bounded region $A$ in $R^d$, $d \geq 2$, having a smooth boundary. The coverage threshold $T_n$ is the smallest $r$ such that the union $Z$ of Euclidean balls of radius $r$ centred on the sample points covers $A$. The connectivity threshold $K_n$ is twice the smallest $r$ required for $Z$ to be connected. These thresholds are random variables determined by the sample, and are of interest, for example, in wireless communications, set estimation, and topological data analysis. We discuss recent results on the large-$n$ limiting distributions of $T_n$ and $K_n$. When $A$ has unit volume, with $v$ denoting the volume of the unit ball in $R^d$ and $|dA|$ the perimiter of $A$, these take the form of weak convergence of $ n v T_n^d - (2-2/d) \log n - a_d \log (\log n) $ to a Gumbel-type random variable with cumulative distribution function $$ F(x) = \exp (-b_d e^{-x} - c_d |dA| e^{-x/2}), $$ for suitable constants $a_d, c_d$ with $b_2 =1$, $b_d =0 $ for $d>2$. The corresponding result for $K_n$ takes the same form with different constants $a_d, c_d$. If time permits, we may also discuss extensions and related results concerning (i) Other domains $A$ such as polytopes or manifolds; (ii) coverage by balls of random radii; (iii) strong laws of large numbers for $T_n$ and $K_n$ for non-uniform random samples of points. Some of the work mentioned here is joint work with Xiaochuan Yang and Frankie Higgs. via Zoom 2025-10-07 10:30:00 11:30:00 Probability and Dynamics seminar Mathew Penrose Bath, UK 3549 Maud Menten Lecture: Spatial Pattern Formation and the Evolution of Cooperative Behaviour CLE A317 and Zoom 2025-10-06 12:00:00 13:00:00 Math biology seminar Dan Clooney University of Illinois, Urbana Champaign 3538 The Search for Hamilton Cycles ABSTRACT: The question of whether one graph can be embedded in another is a fundamental problem in graph theory. In 2020, Joos and Kim introduced a generalization of the basic graph embedding problem to graph collections. Let G={G_1,...,G_m} be a collection of not necessarily distinct graphs on a common vertex set V with |V|=n. Given a graph H with at most m edges, a rainbow copy of H in G is a copy of H on V using at most one edge from each graph G_i. Joos and Kim showed that Dirac's Theorem can be generalized to this setting; that is, if m=n and the minimum degree of each graph in G is at least n/2, then G contains a rainbow Hamilton cycle. Recently, Bowtell, Morris, Pehova, and Staden proved an asymptotically best possible strengthening of this result when we instead require the existence of Hamilton cycles with every possible edge-colouring. We prove a version of their result for powers of Hamilton cycles. Based on work with Emily Heath, Joseph Hyde, and Natasha Morrison. MAC D101 2025-10-02 10:00:00 11:00:00 Discrete math seminar Shannon Ogden University of Victoria 3564 Gysin sequences for boundary actions (Part 1 of 2) Abstract: We explain how the Baum-Connes conjecture can be used to compute the K-theory of the crossed product C*-algebras obtained from actions of groups acting on `boundaries at infinity' in the form of an analogue of the Gysin sequence from algebraic topology. CLE D134 2025-10-01 15:30:00 16:45:00 Operator theory seminar Heath Emerson University of Victoria 3563 A random walk approach to high-dimensional critical phenomena Abstract: One of the main goals of statistical mechanics is to understand critical phenomena of lattice models. This can be achieved by computing the so-called critical exponents, which govern algebraic scaling near or at the critical point. This task is generally impossible due to the intricate interplay between the specific features of the models and the geometry of the graphs on which they are defined. A striking observation was made in the 20th century: above the upper critical dimension d_c, the geometry becomes inessential and critical exponents adopt their mean-field values (as on Cayley trees or complete graphs). Classical approaches—renormalization group, differential inequalities with reflection positivity, and the lace expansion—are powerful yet model-specific and technically heavy. We revisit the study of the mean-field regime and introduce a unified, probabilistic framework that applies across perturbative settings, including weakly self-avoiding walk (d>4), spread-out Bernoulli percolation (d>6), and one- and two-component spin models (d>4). Based on ongoing works with Hugo Duminil-Copin, Aman Markar, and Gordon Slade. via Zoom 2025-09-30 10:30:00 11:30:00 Probability and Dynamics seminar Romain Panis University of Lyon 3548 Parameter identification of age-structured epidemic models Parameter identifiability analysis aims to determine whether model parameters can be uniquely determined from observable outputs. This is a critical step in epidemiological forecasting and the design of effective control measures. In this talk, we systematically review the theoretical foundations and practical applications of parameter identifiability and propose a framework for analyzing structural model parameter identifiability. By integrating locally and globally identifiable techniques, we systematically construct a hierarchical structure for parameter identifiability in age-structured epidemic models. Using Monte Carlo simulations and approximate Bayesian estimation methods, we identify parameters that are actually unidentifiable in the models. This is a joint work with Ziyi Wu and Maia Martcheva. CLE A317 2025-09-29 12:00:00 13:00:00 Math biology seminar Junyuan Yang Shanxi University 3558 PIMS Network-wide Colloquium: The question mark function, welding and complex dynamics Please <a href="https://ubc.zoom.us/meeting/register/OoGJFra5SMiLY8pSQJqhJw#/registration">register here</a>. via Zoom registration required 2025-09-25 13:30:00 14:30:00 PIMS lectures Curtis McMullen Harvard University 3537 Haiman ideals, link homology, and affine Springer fibers Abstract: We will discuss a class of ideals in a polynomial ring studied by Mark Haiman in his work on the Hilbert scheme of points and discuss how they are related to homology of affine Springer fibers, Khovanov-Rozansky homology of links, and to the ORS conjecture. We will do some explicit examples of computing KR-homology using combinatorial link recursions developed by Elias and Hogancamp. MAC D101 2025-09-25 10:00:00 11:00:00 Discrete math seminar Joshua P Turner University of British Columbia 3547 Maud Menten Lecture: Modelling the ecology and evolution of post-infection mortality Join Zoom Meeting <a href="https://uvic.zoom.us/j/81909983859">https://uvic.zoom.us/j/81909983859</a> Pathogens can cause long-term damage to their hosts, leading to potentially elevated mortality after recovery. While such ‘post-infection mortality’ may be widespread, its ecological and evolutionary dynamics remain largely unexplored. In this talk, I will begin by using a simple mathematical model to investigate the epidemiological impacts of post-infection mortality in a variety of settings. I will then discuss various model extensions. Finally, I will use an eco-evolutionary model to study the evolution of post-infection mortality. CLE A317 and Zoom 2025-09-22 12:00:00 13:00:00 Math biology seminar Chadi Saad-Roy University of British Columbia 3545 Degree thresholds for odd cycle decompositions An F-decomposition of a graph G is a set of subgraphs of G, each isomorphic to F, whose edge sets partition the edge set of G. I will speak about a result showing that, for each odd k ≥ 5, any graph G of sufficiently large order n with minimum degree at least (1/2+1/(2k-4)+o(1))n has a C_k-decomposition if and only if k divides |E(G)| and all vertex degrees in G are even. Our methodology also leads to results on F-decompositions for other 3-partite graphs F. This is joint work with Darryn Bryant, Daniel Horsley, Barbara Maenhaut and Richard Montgomery. MAC D101 2025-09-18 10:00:00 11:00:00 Discrete math seminar Peter Dukes University of Victoria 3546 The Jiang-Su algebra Abstract: The Jiang-Su algebra was first constructed as a strange example defying far-sighted conjectures of George Elliott. Since, it has gone on the be a cornerstone of the Elliott classification program for separable, amenable C*-algebras. I will give a gentle introduction, needing only a superficial knowledge of C*-algebras. CLE D134 2025-09-17 15:30:00 16:45:00 Operator theory seminar Ian Putnam University of Victoria 3544 Deep Learning Methods for Cell Type Annotation in Single-Cell RNA Sequencing Examining Committee Supervisory Committee Dr. Xuekui Zhang, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Xiaojian Shao, Department of Mathematics and Statistics, UVic (Co-Supervisor) Dr. Belaid Moa, Department of Electrical and Computer Engineering, UVic (Outside Member) External Examiner Dr. Pingzhao Hu, Department of Biochemistry, Western University Chair of Oral Examination Dr. Michael McGuire, Department of Electrical and Computer Engineering, UVic Abstract This dissertation presents a systematic exploration of scalable, interpretable, and high-accuracy computational frameworks for automated cell type classification in scRNA-seq data. The research spans three major contributions, each addressing different trade-offs between simplicity, interpretability, and predictive power: <ol> <li>PCLDA (Penalized Component-wise Linear Discriminant Analysis) introduces a highly interpretable and statistically grounded annotation tool.</li> <li> scSorterDL expands on this foundation by combining penalized LDA with ensemble learning and deep neural networks. </li> <li> CellAnnotatorNet represents the culmination of this research by integrating a categorical autoencoder with the Swarm-pLDA framework into a unified, fully differentiable architecture. </li> </ol> Together, these three contributions provide a progressive development from classical interpretable models to fully integrated deep learning pipelines for large-scale single-cell analysis. via Zoom 2025-09-15 09:00:00 10:00:00 Graduate dissertations Kailun Bai University of Victoria 3536 The log-rank conjecture: New Equivalent Formulations Abstract: The log-rank conjecture is a longstanding open problem with multiple equivalent formulations in complexity theory and mathematics. In its linear-algebraic form, it asserts that the rank and partitioning number of a Boolean matrix are quasi-polynomially related. In this talk, I will present a relaxed but still equivalent version of the conjecture based on a new matrix parameter, $\pm$-rank: the minimum number of all-1 rectangles needed to express the Boolean matrix as a $\pm 1$-sum. $\pm$-rank lies between rank and partition number, and our main result shows that it is in fact equivalent to rank up to a logarithmic factor. This reframes the log-rank conjecture as: can every signed decomposition of a Boolean matrix be made positive with only quasi-polynomial blowup? Additionally, I will show that the log-rank conjecture is equivalent to a conjecture on cross-intersecting set systems. The talk is based on joint work with Shachar Lovett and Morgan Shirley. Cle D130 2025-09-11 10:00:00 11:00:00 Discrete math seminar Lianna Hambardzumyan University of Victoria 3535 The Ramsey Multiplicity Problem See <a href="https://www.uvic.ca/science/math-statistics/assets/docs/abstracts/2025-08-21-lee.pdf">announcement (PDF)</a>. Clearihue Building Room B019 2025-08-21 09:00:00 10:00:00 Graduate dissertations Jae-Baek Lee University of Victoria 3534 Permutation in Regression Revisited: The Residual Route Proven Optimal Theoretically Notice of the Final Oral Examination for the Degree of Master of Science of SOOJEONG KIM BSc (Kyungpook National University, 2015) Permutation in Regression Revisited: The Residual Route Proven Optimal Theoretically Department of Mathematics and Statistics Thursday, August 14, 2025 1:00 P.M. David Turpin Building Room A203 Supervisory Committee: Dr. Xuekui Zhang, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Mary Lesperance, Department of Mathematics and Statistics, UVic (Member) External Examiner: Dr. Alex Thomo, Department of Computer Science, UVic Chair of Oral Examination: Dr. Jody Klymak, School of Earth and Ocean Sciences, UVic Abstract The assumptions for classical linear-model are never met in practice. Recent evidence shows that such violations inflate Type I error as sample size grows, while simple permutation tests can restore control in single-predictor regressions. Yet in multiple regression, practitioners face a confusing menu of residual- and raw-data shuffling schemes, with little theory to guide the choice. We develop the first closed-form, finite-sample comparison of six widely used permutation strategies for a coefficient of interest in the presence of nuisance covariates. By projecting any full-rank regression onto an equivalent two-predictor "working" model and treating the permutation matrix itself as random, we derive exact means and variances of the permuted estimator, and we establish its asymptotic distribution. The analysis reveals that (i) the three residual-based schemes—permuting response residuals, predictor residuals, or both—are identically distributed; they match the parametric null up to second moments in finite samples and match in distribution as as n approaches infinity, guaranteeing valid Type I error control. (ii) Raw-data permutations behave unpredictably: shuffling the response is overly conservative, shuffling the predictor is liberal when covariates are correlated, and shuffling both can be unstable. Closed-form results quantify how predictor–covariate correlation, error variance, and sample size drive these patterns and specify the Monte-Carlo sample size needed for accurate p- values. Extensive simulations confirm the theory: residual permutations maintain nominal error and retain power comparable to the classical linear model when assumptions hold, whereas raw-data schemes either inflate or deflate Type I error and sacrifice power. The work reconciles decades of ad-hoc practice, provides actionable guidelines, and equips analysts with a principled, computationally feasible framework for exact inference in large-sample regression. DTB A203 2025-08-14 13:00:00 14:00:00 Graduate dissertations Soojeong Kim University of Victoria 3527 The Radius of Location The metric dimension of a graph represents the minimum number of cell towers needed to be placed among the vertices of a graph such that the position of a hidden agent can be determined using only its distances to each of the cell towers. We introduce the radius of location of graphs, which represents the minimum possible "strength" of the cell towers over all optimal layouts of the towers. In particular, a cell tower cannot distinguish two locations if they are outside of the range of that tower. We give some results for general graphs, and discuss some particular families of graphs, with an emphasis on trees. This is joint work with Danny Dyer and Melissa Huggan. David Strong C128 2025-08-12 11:30:00 12:20:00 Discrete math seminar Logan Pipes Memorial University 3533 Mathematical models of a social-ecological system: coupling lake pollution dynamics and human behavior Join Zoom Meeting <a href="https://uvic.zoom.us/j/86525391769">https://uvic.zoom.us/j/86525391769</a> Humans are a key factor in driving many ecological and environmental dynamics, e.g., through pollution, the exploitation of natural resources, or habitat deterioration. It is therefore imperative to gain a better understanding how human behavior affects the natural systems – and vice versa. In this talk, I will introduce a mathematical model that is deliberately simplified to better understand the mutual feedbacks in a coupled human-environment system. The model consists of an "ecological" part that describes the eutrophication of shallow lakes and a "social" part that describes human behavior in the discharge of nutrients causing eutrophication. The latter uses two approaches from evolutionary game theory, namely replicator dynamics and stochastic best response dynamics, which allow an upscaling from individual behavior to the collective level of a group. I will compare their commonalities and differences. Both the ecological and the behavioral part can exhibit tipping points, where the lake water abruptly shifts from a clear to a turbid state, or where human behavior shifts from high to low pollution activities. Mathematically, this results in up to four alternative stable states, the possibility of sustained social-ecological cycles, and evidence for Bogdanov-Takens bifurcations. Due to the complexity in the social-ecological interaction, it seems impossible to derive a general rule of thumb for how to achieve a desirable state. Nevertheless, knowing the dynamics of a system in question can help comparing management strategies and preventing undesired consequences. (Joint work with Anthony Sun.) David Strong Building C-118 and Zoom 2025-07-28 12:00:00 13:00:00 Math biology seminar Frank Hilker University of Osnabruck https://bit.ly/2025-07-28-hilker 3532 Broadcast Independence and Broadcast Packing See <a href="https://www.uvic.ca/science/math-statistics/assets/docs/abstracts/2025-07-11-mcdonald.pdf">announcement (PDF)</a>. CLE B019 2025-07-11 10:00:00 11:00:00 Graduate dissertations Kiara McDonald University of Victoria 3530 Renormalized limits of the stochastic heat equation and the Kardar-Parisi-Zhang equation in high dimensions Examining Committee Supervisory Committee Dr. Yu-Ting Chen, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Anthony Quas, Department of Mathematics and Statistics, UVic (Member) Dr. Kristan Jensen, Department of Physics and Astronomy, UVic (Outside Member) External Examiner Dr. Clément Cosco, Centre de recherche en mathématiques de la decision, Université Paris-Dauphine Chair of Oral Examination Dr. Falk Herwig, Department of Physics and Astronomy, UVic Abstract This thesis investigates the mollified versions of the stochastic heat equation (SHE) and the Kardar–Parisi–Zhang (KPZ) equation in high dimensions (d ≥ 3), focusing on their limiting behaviors as the mollification is removed. These limiting behaviors are closely related to a key parameter, known as the coupling constant, which characterizes the strength of the driving noise. 34 The first part of this article analyzes the space-time fluctuations of the mollified SHE and mollified KPZ equation around their stationary states. These rescaled fluctuations, previously considered in [23, 24], provide a new viewpoint for describing the convergence of the above mollified equations. For every coupling constant that is strictly less than a specific critical threshold, called the L2-critical point, we establish Gaussian limits, possibly with additional random perturbations, for these rescaled fluctuations. The second part of this article investigates the limiting higher moments for the mollified SHE in high dimensions. Motivated by a recent result [21] in two dimensions, a natural question is whether the higher moments also converge at the L2-critical point in high dimensions. Our main theorem gives a negative answer: in high dimensions, the limiting higher moments diverge for all coupling constants in a nontrivial interval containing the L2-critical point. As an application, we derive sharp estimates for quantities, which are believed to be closely related to probability distributions of the limiting partition function of the continuous directed polymer. As a follow-up investigation, the third part of this article analyzes the above conjecture on the higher moments in three dimensions by considering a specific version of the limiting higher moment at the L2-critical point, referred to as the sub-limiting higher moment. This special limiting higher moment can be regarded as a three-dimensional analogue of the limiting higher moment in two dimensions at the corresponding L2-critical point, established in [21]. Our main result proves the spatial pointwise divergence of this limiting object. This divergence can be related to a well-known phenomenon in quantum physics known as the Efimov effect. via Zoom 2025-07-10 08:30:00 09:30:00 Graduate dissertations Te-Chun Wang University of Victoria 3531 Chordality of Digraphs, Signed Graphs, and Signed Bigraphs Notice of the Final Oral Examination for the Degree of Doctor of Philosophy of YING YING (FAY) YE MSc (University of Victoria 2019) MSc (University of Victoria 2008) BSc (University of Victoria 2007) “Chordality of Digraphs, Signed Graphs, and Signed Bigraphs” Department of Mathematics and Statistics Tuesday, July 8, 2025 10:00 A.M. David Turpin Building Room A203 Supervisory Committee: Dr. Jing Huang, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Jonathan Noel, Department of Mathematics and Statistics, UVic (Member) Dr. Venkatesh Srinivasan, Department of Computer Science, UVic (Outside Member) External Examiner: Prof. Shamik Ghosh, Department of Mathematics, Jadavpur University Chair of Oral Examination: Dr. David Scoones, Department of Economics, UVic Abstract Chordal graphs and chordal bigraphs enjoy beautiful characterizations, in terms of forbidden subgraphs, vertex or edge orderings, and tree-like representations. A digraph analogue of chordal graphs was introduced by Haskins and Rose. Unfortunately, a forbidden subdigraph characterization of chordal digraphs is not known and finding such a characterization seems to be a difficult problem. The study of chordal digraphs has been restricted to various classes of digraphs, such as semicomplete digraphs, quasi-transitive digraphs, extended semicomplete digraphs and locally semicomplete digraphs. In this dissertation, we introduce the new class of weakly quasi-transitive digraphs as a common generalization of semicomplete digraphs, quasi-transitive digraphs and symmetric digraphs. We show that weakly quasi-transitive digraphs can be obtained from these three classes of digraphs by substitutions. As a consequence, weakly quasitransitive digraphs admit a recursive construction. This construction theorem allows us to find a forbidden subdigraph characterization of weakly quasi-transitive chordal digraphs. In addition, we use it to prove that the small quasi-kernel conjecture holds for weakly quasi-transitive digraphs. We extend the notion of chordality to signed graphs and signed bigraphs Interestingly, chordal signed graphs are equivalent to strict chordal digraphs studied by Hell and Hernandez-Cruz. Their forbidden subdigraph characterization of strict chordal digraphs can be translated to a forbidden subgraph characterization of chordal signed graphs. We give a forbidden subgraph characterization of chordal signed bigraphs. The forbidden subgraphs for chordal signed bigraphs are analogous to those for chordal signed graphs but the proofs are much more complicated and intriguing. DTB A203 2025-07-08 10:00:00 11:00:00 Graduate dissertations Ying Ying (Fay) Ye University of Victoria 3529 Modelling Infectious Disease - from Genomes to Populations Abstract: Host-pathogen interactions underlying the development and spread of infectious diseases can be modelled at multiple scales - from pathogen genome analysis to epidemiological compartment modelling of the host populations. It is also a highly interdisciplinary area requiring data inputs and modelling methods from all Sciences. I will summarize our work on HIV-1 genome analysis using the Chaos Game Representation, modelling HIV-1 Reverse Transcriptase protein (a drug-target) using Graph Theory, and elaborate on mathematical and statistical modelling of Malaria with reference to prevalence data from India. DSB C116 2025-06-18 14:30:00 15:30:00 Math biology seminar Somdatta Sinha IISER India 3528 Modelling Infectious Disease - from Genomes to Populations Abstract: Host-pathogen interactions underlying the development and spread of infectious diseases can be modelled at multiple scales - from pathogen genome analysis to epidemiological compartment modelling of the host populations. It is also a highly interdisciplinary area requiring data inputs and modelling methods from all Sciences. I will summarize our work on HIV-1 genome analysis using the Chaos Game Representation, modelling HIV-1 Reverse Transcriptase protein (a drug-target) using Graph Theory, and elaborate on mathematical and statistical modelling of Malaria with reference to prevalence data from India. DSB C116 2025-06-18 14:30:00 15:30:00 Applied math seminar Somdatta Sinha IISER India 3526 The Calogero-Sutherland derivative NLS equation Abstract: We consider a type of nonlocal nonlinear derivative Schrödinger equation on the torus, called the Calogero-Sutherland DNLS equation. We derive an explicit formula to the solution of this nonlinear PDE. Moreover, using the integrability tools, we establish the global well-posedness of this equation in all the Hardy-Sobolev spaces $H^s_+(\T)$, $s\geq 0$ down to the critical regularity space, and under a mass assumption on the initial data for the focusing equation, and for arbitrary initial data for the defocusing equation. Finally, a sketch of the proof for extending the flow to the critical regularity $L^2_+$ will be presented. TBD 2025-06-11 13:30:00 14:30:00 Applied math seminar Rana Badreddine UCLA