Western Math Calendar

Mathematics Calendar

May 2026

Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
26	27 Ph.D. Public Lecture 14:00 Yucen Jin (Western) Delay-induced bifurcations and chaos dynamics in a host competitor parasite model Ph.D. Public Lecture Speaker: Yucen Jin (Western) "Delay-induced bifurcations and chaos dynamics in a host competitor parasite model" Time: 14:00 Room: MC 108 : Latency is a feature of nearly all real-world biological systems, yet many models simplify analysis by assuming such delays to be negligible. Here we examine a three-dimensional host–competitor–parasite model in which a maturation delay is introduced in the parasite’s reproduction term. We analyze how this latency alters the system’s dynamics, particularly its ability to generate more complex bifurcations. In the delayed model, we identify delay-induced Hopf bifurcations, a generalized Hopf (Bautin) point obtained through a fifth-order normal form, and a codimension-two Hopf–zero bifurcation arising when a boundary transcritical condition intersects the Hopf curve. Beyond local bifurcations, the corresponding non-delayed ODE exhibits a classical period-doubling cascade to chaos. In contrast, the delayed system produces only narrow “chaos windows,” indicating that parasite maturation latency plays a limited role in generating chaos. We also examine bistability between coexistence dynamics, such as periodic or chaotic attractors, and a boundary equilibrium, and we discuss how the introduction of delay influences the extent of this bistability. Geometry and Combinatorics 15:30 Prajwal Udanshive (Western) arrangement properties of simple Schubert matroids Geometry and Combinatorics Speaker: Prajwal Udanshive (Western) "arrangement properties of simple Schubert matroids" Time: 15:30 Room: MC 107	28	29 Homotopy Theory 14:00 Daniel Carranza (Johns Hopkins University) The Discrete Homotopy Hypothesis for n-types Homotopy Theory Speaker: Daniel Carranza (Johns Hopkins University) "The Discrete Homotopy Hypothesis for n-types" Time: 14:00 Room: MC 107 Homotopy Theory 15:30 Mark Behrens (University of Notre Dame) The degree spectral sequence Homotopy Theory Speaker: Mark Behrens (University of Notre Dame) "The degree spectral sequence" Time: 15:30 Room: MC 107	30 Homotopy Theory 10:00 Nathan Kershaw (Western) Computations of discrete homology Homotopy Theory Speaker: Nathan Kershaw (Western) "Computations of discrete homology" Time: 10:00 Room: MC 107 Homotopy Theory 11:30 Jacob Ender (Western) Towards the basic shapes conjecture Homotopy Theory Speaker: Jacob Ender (Western) "Towards the basic shapes conjecture" Time: 11:30 Room: MC 107	1	2
3	4 Transformation Groups Seminar 10:30 Vladimir Gorchakov (Western) Stanley–Reisner Rings as Equivariant Cohomology Rings Transformation Groups Seminar Speaker: Vladimir Gorchakov (Western) "Stanley–Reisner Rings as Equivariant Cohomology Rings" Time: 10:30 Room: MC 108 In this talk, we will discuss a connection between the localization theorem in equivariant cohomology and localization of Stanley-Reisner rings.	5 Geometry and Topology 11:00 Michael Lesnick (SUNY Albany) Lectures on Multiparameter Persistence I: Density-sensitive bifiltrations in TDA Geometry and Topology Speaker: Michael Lesnick (SUNY Albany) "Lectures on Multiparameter Persistence I: Density-sensitive bifiltrations in TDA" Time: 11:00 Room: MC 204	6 Geometry and Topology 11:00 Michael Lesnick (SUNY Albany) Lectures on Multiparameter Persistence II: Lp-metrics on multiparameter persistence modules Geometry and Topology Speaker: Michael Lesnick (SUNY Albany) "Lectures on Multiparameter Persistence II: Lp-metrics on multiparameter persistence modules" Time: 11:00 Room: MC 204	7 Geometry and Topology 11:00 Michael Lesnick (SUNY Albany) Lectures on Multiparameter Persistence III: Limit computation via minimal initial functors Geometry and Topology Speaker: Michael Lesnick (SUNY Albany) "Lectures on Multiparameter Persistence III: Limit computation via minimal initial functors" Time: 11:00 Room: MC 204	8	9
10	11 Geometry and Combinatorics 15:30 Anton Dochtermann (Texas State University) TBA Geometry and Combinatorics Speaker: Anton Dochtermann (Texas State University) "TBA" Time: 15:30 Room: MC 108	12	13 Geometry and Topology 14:00 Alex Suciu (Northeastern University) Koszul linearization and invariants of non-formal cdga models Geometry and Topology Speaker: Alex Suciu (Northeastern University) "Koszul linearization and invariants of non-formal cdga models" Time: 14:00 Room: MC 107 I will present a method for computing resonance varieties, Alexander invariants, and Chen ranks of spaces that are not formal but admit finite-type cdga models. The method is based on Koszul linearization, which replaces the classical algebraic constructions underlying Alexander-type invariants with functorial algebraic objects built directly from the cdga, thereby shifting the role of the cohomology ring to the full model. A key feature of this approach is the existence of functorial spectral sequences that interpolate between invariants computed from cohomology and those arising from the cdga model, with higher differentials encoding iterated Massey products. This framework yields extensions of several results from the formal setting, including the fact that cohomology controls the first-order behavior at the origin of the resonance varieties, as well as explicit formulas for infinitesimal Alexander invariants and Chen ranks in terms of the model. Discrepancies between cohomological and model-theoretic invariants thus provide computable obstructions to formality. The constructions are functorial with respect to cdga morphisms and provide effective tools for computation. Applications include nilpotent Lie algebras and elliptic configuration spaces, as well as consequences for detecting non-formality. Geometry and Topology 15:30 Anton Dochtermann (Texas State University) TBA Geometry and Topology Speaker: Anton Dochtermann (Texas State University) "TBA" Time: 15:30 Room: MC 107	14	15	16
17	18	19	20	21 Colloquium 15:30 Ido Efrat (Ben-Gurion University) Absolute Galois groups - Old and New Results Colloquium Speaker: Ido Efrat (Ben-Gurion University) "Absolute Galois groups - Old and New Results" Time: 15:30 Room: MC 107	22	23
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31	1	2	3 PhD Thesis Defence 13:00 Siyuan Yu (Western) TBA PhD Thesis Defence Speaker: Siyuan Yu (Western) "TBA" Time: 13:00 Room: MC 107 Mathematics Departmental Presentation 2026 15:30 Thomas Thorbjørnsen (Western) TBA Mathematics Departmental Presentation 2026 Speaker: Thomas Thorbjørnsen (Western) "TBA" Time: 15:30 Room: MC 108	4 Ph.D. Candidacy Exam Lecture 10:00 Theo Chatzidiamantis Christoforidis (Western) TBA Ph.D. Candidacy Exam Lecture Speaker: Theo Chatzidiamantis Christoforidis (Western) "TBA" Time: 10:00 Room: MC 107 Ph.D. Candidacy Exam Lecture 14:00 Zack Dooley (Western) TBA Ph.D. Candidacy Exam Lecture Speaker: Zack Dooley (Western) "TBA" Time: 14:00 Room: MC 107	5	6