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Events for December 2025 – April 2026

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Tue, Dec. 2 1:25pm (online)	Algebra/Logic Andrea Montoli (Universita degli Studi di Milano) View Online:https://cuboulder.zoom.us/j/96896272260 X We will describe some categorical properties of preordered and right-preordered groups, giving an explicit description of limits and colimits in these categories, studying some exactness properties, and showing that both structures give rise to quasivarieties. We will show that, from an algebraic point of view, the categories of preordered groups and of right-preordered groups share several properties with the one of monoids. Joint work with Maria Manuel Clementino and Nelson Martins-Ferreira. (Right-)preordered groups from a categorical perspective
Wed, Dec. 3 4:40pm (MATH 3…	Grad Student Seminar Stephanie Oh (CU Boulder) X Spectral sequences are fundamental computational tools in algebraic topology/geometry and homotopy theory. In this talk, I will give an example-driven introduction to spectral sequences. Some familiarity with homological algebra and/or Top 2 will be helpful. What even is a spectral sequence?
Fri, Dec. 12 1:30pm (Math 2…	Noncomm Geometry Vladimir Baranovsky (University of California, Irvine) X Let (M, w) be a complex manifold with an holomorphic symplectic form, or an algebraic version of such a pair. Consider also a pair (X, E) consisting of a coisotropic submanifold X in M and a vector bundle E on X. Then (local) sections of E form a module over the ring O of (local) functions on M. Given a deformation quantization O_h of functions, one can ask whether E admits a similar deformation quantization E_h as a module over O_h. For Lagrangian X this is equivalent to existence of a projectively flat connection on E with specific properties. For general coisotropic X only necessary conditions on some characteristic classes are known. The plan is to present some results and conjectures related to the problem, based on recent work of Bogdanova-Vologodsky and a Harish-Chandra bundle approach to quantizations and their Deligne classes, introduced earlier by Bezrukavnikov-Kaledin. Quantization of symplectic manifolds and vector bundles on coisotropic submanifolds.
Tue, Dec. 16 3:30pm (MATH 3…	Topology Bowen Yang (Harvard Center of Mathematical Sciences and Applications) X I will outline a classification framework for quantum phases within the setting of stabilizer states and quantum cellular automata (QCA). Both admit a precise algebraic formulation—stabilizer codes as modules over Laurent polynomial rings, and QCA as locality-preserving automorphisms of operator algebras—through which topological invariants such as Witt classes and boundary charge modules arise. I will review my recent work classifying Clifford QCA and Pauli stabilizer codes, which fit naturally into the same mathematical framework. A Case Study in the Classification of Quantum Phase Sponsored by the Meyer Fund
Wed, Jan. 14 4:40pm (MATH 3…	Grad Student Seminar Basia Klos (CU Boulder) X Does that question keep you up at night? If yes, you're in luck - in this talk, we'll define these algebraic objects, which are ubiquitous in the representation theory of infinite-dimensional Lie algebras and also appear in number theory and physics. We'll give a friendly example of a VOA and might even mention why you should care. What even is a vertex operator algebra?
Thu, Jan. 15 11:15am (MATH …	Algebraic Geometry AG Group Organizational meeting
Thu, Jan. 22 2:30pm (MATH 3…	Functional Analysis Dorin Dumitrascu (Adrian College) X I will discuss some aspects of the bivariant K-theory developed by Le Gall. (P. Y. LeGall, Th\'eorie de Kasparov \'equivariante et groupo\"{\i}des. I, K-Theory 16 (1999), 361--390.) Equivariant KK-theory for groupoids acting on C*-algebras (after Le Gall)
Tue, Jan. 27 1:25pm (online)	Algebra/Logic David Stanovsky (Charles University) View Online:https://cuboulder.zoom.us/j/96896272260 X How many groups of order n are there, up to isomorphism? And what about quasigroups, semigroups, and other types of algebraic structures? Why the combinatorial explosion for quasigroups and semigroups, and not for groups? Or, actually, what is the true asymptotic behavior behind enumeration of groups? I will show some number series. I will briefly discuss enumeration methods. I will start with a brief overview of classical results on groups. In the second half of the talk, I will turn to the class of quandles, which provides an exciting playground for various types of enumeration methods. Enumeration of groups and quandles
Tue, Jan. 27 5pm (Math 350)	Math Club Siddhant Agrawal X The Navier Stokes equation is a partial differential equation that describes the motion of viscous fluids. It arises naturally in engineering and other scientific fields. In this talk, we'll derive the Navier Stokes equation and discuss some of its basic properties. We'll also discuss the famous Millennium Prize Problem concerning the Navier Stokes equation. Note: The recommended prerequisite for this talk is Calculus 3, but all are welcome! What is the Navier Stokes Equation?
Thu, Jan. 29 11:15am (MATH …	Algebraic Geometry Bob Kuo (University of Colorado Boulder) X Mustafin varieties are a particular class of degenerations of projective space. Projective space, and their subvarieties, have many nice properties. Thus, one might wonder what aspects of projective geometry transfers over to Mustafin varieties. In this talk, we will explore this question through the use of tropical geometry. In particular, we will discuss the Picard group of Mustafin varieties, then describe an analogue of Bezout's theorem for Mustafin varieties. A degenerate analogue of projective geometry
Thu, Jan. 29 2:30pm (MATH 3…	Functional Analysis Dorin Dumitrascu (Adrian College) X I will give the definition of Le Gall for the equivariant KK-theory under the action of a Hausdorff groupoid, propose a construction for locally compact locally Hausdorff groupoids, and work out an example coming from foliations. Equivariant KK-theory for groupoids acting on C*-algebras (part 2)
Fri, Jan. 30 12:20pm (Math …	Math Edu Rebekah Jones X Join us to discuss potential topics and speakers for the Seminar on Undergraduate Math Education (SUME) this semester. We encourage all those interested in attending SUME this semester to attend! We'll also spend some time exploring mathematical autobiography assignments—their purpose, how they can support certain instructional goals, and considerations for implementing these assignments in a math classroom. Following our discussion, participants will have the opportunity to write their own brief mathematical autobiographies and share reflections from the experience. Attendees are encouraged (but not required) to read the recent paper on this topic linked below. https://doi.org/10.1080/10511970.2025.2571610 SUME Open House / Discussion of mathematical autobiography assignments
Tue, Feb. 3 12:10pm (MATH …	Kempner David Renfrew (SUNY Binghamton) X We show for a large class of entire functions, f, that after proper rescaling, on compact sets, the derivatives of f converge to cosine, in particular their roots become evenly spaced. This proves a conjecture of Farmer and Rhoades [Trans. Amer. Math. Soc., 357(9):3789–3811, 2005] and Farmer [Adv. Math., 411:Paper No. 108781, 14, 2022] for our class of entire functions. A main ingredient of our proof is to show that high derivatives of high degree polynomials behave like Hermite polynomials, which we prove using the techniques from the newly developed field of finite free probability. This is joint work with Andrew Campbell and Sean O'Rourke. Universality for roots of derivatives of entire functions
Tue, Feb. 3 1:25pm (online)	Algebra/Logic Sara Ugolini (IIIA-CSIC Barcelona) View Online:https://cuboulder.zoom.us/j/96896272260 X In this talk, we begin by considering the semiring of the natural numbers with truncated difference, N = (N, +, *, -, 0, 1). Its equational theory is not recursively axiomatizable, due to the fact that one can essentially encode in it the undecidability of Hilbert’s tenth problem. Our aim is to study finitely axiomatizable varieties of semirings with difference which include the one generated by N, and are as close to it as possible. To this end, we introduce the variety of almost natural semirings with difference, AN. We show that the subdirectly irreducible algebras in this variety coincide with the models of PA, a weak form of Peano Arithmetic without induction that is an axiomatic extension of Robinson Arithmetic. Models of PA are known to satisfy all Sigma_1 sentences true in N. This variety can be axiomatized by a few simple equations and enjoys several appealing universal-algebraic properties: it is connected to lattice-ordered rings, it is a discriminator variety, ideal determined and 0-regular; thus it admits an associated 0-assertional logic. Nevertheless, we will see that its connection to arithmetic still yields an undecidable equational theory. This talk is based on ongoing joint work with Guillermo Badia, Xavier Caicedo, and Carles Noguera. Almost natural semirings with difference
Wed, Feb. 4 2:10pm (MATH350)	Math Phys Markus Pflaum (CU Boulder) X The semester theme will be the mathematics of Schrödinger operators and applications in quantum many-body theory and quantum chemistry. The meeting will be an introductory and organizational meeting. For more please see the seminar webpage under https://math.colorado.edu/mathphysics/ Intro to Schrödinger operators and semester theme
Tue, Feb. 10 1:25pm (online)	Algebra/Logic Claudia Muresan (University of Bucharest) View Online:https://cuboulder.zoom.us/j/96896272260 Abstracting congruence extensions through complete join–semilattice morphisms between commutator lattices
Tue, Feb. 10 5pm (Math 350)	Math Club Nat Thiem X Come hear about the math department's summer REU program! REU stands for Research Experiences for Undergrads. Our summer REU program is an opportunity for you to gain experience and see what math research is like. Once available, descriptions of the different projects will be posted at www.colorado.edu/math/undergraduate-program/summer-research-undergraduate. Or come to the info session to hear about the projects and get your questions answered! Summer REU Info Session
Wed, Feb. 11 2:10pm (Math350)	Math Phys Gregory Berkolaiko (Texas A&M University) View Online:https://cuboulder.zoom.us/j/97049173677 X As a warm-up for the semester, we will explore the time evolution in a finite-dimensional (d=2 mostly) Schrödinger equation, its relation to the quadratic form and their visualization on the Bloch sphere. If time permits, we will briefly discuss why a 2-dimensional picture is sometimes appropriate even when working with unbounded Schrödinger operators. Warm-up: Visualizing Schrödinger's equation in finite dimensions
Wed, Feb. 11 4:40pm (MATH 3…	Grad Student Seminar Colin Jackson X What makes a function earn the title of a zeta function? We will start by looking at the Riemann zeta function, and then generalizations of it and see that if it walks like a zeta function and quacks like a zeta function, then its a zeta function Zeta Function 101
Thu, Feb. 12 11:15am (MATH …	Algebraic Geometry Bob Kuo X In this talk, we'll discuss tropical and toric geometry, and a relationship between the two given by Mustafin varieties. A degenerate analogue to projective geometry part II
Thu, Feb. 12 2:30pm (MATH 3…	Functional Analysis Robin Deeley (CU Boulder) X I will introduce a class of dynamical systems called shifts of finite type. There are a number of C-algebras one can construct from a shift of finite type. I will discuss properties of these C-algebras such as rational Poincare duality and rational isomorphism. Rationalizing shifts of finite type - Part I
Fri, Feb. 13 12:20pm (MATH …	Math Edu Shelby Stanhope (US Air Force Academy) View Online:https://cuboulder.zoom.us/j/99367133807 X Students often find the transition from two-dimensional to three-dimensional thinking in multivariable calculus challenging. Computer visualization and tactile models can help bridge this gap and deepen students’ spatial understanding of concepts. CalcPlot3D is a free, web-based applet for 3D graphing that is easy for students and instructors to use due to its code-free, menu-driven interface with fillable textboxes, dropdown lists, and checkboxes. In this presentation, I will show demonstrations that instructors can use to illuminate concepts and visualizations that students can easily create themselves. In addition, I will discuss several classroom activities that incorporate 3D-printed models, allowing students to physically explore concepts in small groups. Together, these tools provide engaging ways for instructors to support student learning and help cultivate stronger geometric intuition in multivariable calculus. Supporting conceptual understanding in multivariable calculus using computer visualization and classroom activities with 3D-printed models
Tue, Feb. 17 2:30pm (MATH 3…	Lie Theory Carlos Ortiz (Colorado State University) X A fundamental problem in topology is to determine when two spaces are distinct. For surfaces, classical invariants suffice, but for three-dimensional manifolds the question is considerably harder. The Witten-Reshetikhin-Turaev invariants, originating in quantum field theory, provide one family of tools. For torus bundles, i.e. 3-manifolds built by cutting a torus, applying a mapping class in SL(2,Z), and regluing, the skein algebra embeds into a non-commutative torus at roots of unity, yielding a finite-dimensional representation that makes these invariants concretely computable. Exploiting this structure, we develop a classical dynamic programming algorithm and a quantum algorithm that encodes the computation into logarithmically many qubits, achieving an exponential reduction in space. We further identify a natural coefficient-counting problem that is #P-complete yet admits efficient quantum approximation. The first half of the talk will be expository, requiring only linear algebra and modular arithmetic. The second half will outline the algorithmic results. How to tell shapes apart using quantum computers
Tue, Feb. 17 3:30pm (MATH 3…	Topology Gregory Berkolaiko (Texas A&M) X The Rayleigh-Ritz method approximates the eigenvalues of a large Hermitian matrix B with Ritz values, which are the eigenvalues of B's restriction() to a smaller trial subspace S. We can view the k-th Ritz value as a real-valued function ("Ritz energy landscape") on the manifold of all possible s-dimensional trial subspaces, the Grassmannian (or for the real symmetric case). Motivated by questions from quantum chemistry and spectral optimization, this talk explores the topology of the Ritz energy landscape. A Morse function is called "perfect" if it describes the topology of its domain in the most efficient way possible, meaning the number of its critical points of each type exactly matches the corresponding Betti number of the space. We demonstrate that for a matrix B with distinct eigenvalues, the Ritz landscape is indeed perfect. While the function itself is not everywhere smooth and its critical points are not isolated --- and not even Morse-Bott --- its critical structure is nevertheless well-defined and ultimately reflects the topology of the Grassmannian in a minimal, perfect way. To be more precise, we show that the filtration of the Grassmannian by the sublevel sets of the k-th Ritz value is homologically perfect. The proof proceeds by introducing a suitable perturbation which ensures that points of non-smoothness are not critical (by a theorem of Zelenko and the presenter) and that the remaining smooth critical points are isolated. Based on a joint work with Mark Goresky (IAS). Footnote (): the term "restriction" is appropriate in the equivalent formulation of eigenvalues of quadratic forms. For an operator B, we apply it to vectors in S and then project the result orthogonally back onto S; this is called a "compression" of B. Ritz energy landscape is perfect (almost) Morse
Tue, Feb. 17 5pm (Math 350)	Math Club Edouard Heitzmann X The legal standard set in Rucho v Common Cause puts the onus on the plaintiffs in a Voting Rights Act (VRA) case to demonstrate that a map is a racial rather than a partisan gerrymander in order for it to be struck down as unlawful. This means plaintiffs have to 'do the homework' of the defendants for them: they must produce a map that is at least as politically gerrymandered as the defendants drew, while achieving better racial representation outcomes. This standard was successfully met by a group of mathematicians in the El Paso redistricting case, winning in federal court before the Supreme Court shadow docket put a hold on the decision, allowing the racial gerrymander to go through. The mathematicians who accomplished this used Monte Carlo Markov Chain (MCMC) methods to draw a so-called 'ensemble' of millions of alternative congressional maps for Texas, and used statistical methods to show that the enacted map was an outlier for racial representation among the maps that had similar partisan outcomes. In this talk I will go over these mathematical details, as well as describe the computational tools currently used in this field. Note: If you have a working Jupyter Notebook installation, you are encouraged to bring it to the talk, as you will have the opportunity to follow along the computational demos included in the talk. The Mathematics of Redistricting—what they did in Texas
Wed, Feb. 18 2:10pm (Math350)	Math Phys Howy Jordan (CU Boulder) View Online:https://cuboulder.zoom.us/j/97049173677 The spectral theorem and projection valued measures I
Thu, Feb. 19 2:30pm (MATH 3…	Functional Analysis Robin Deeley (CU Boulder) X I will introduce a class of dynamical systems called shifts of finite type. There are a number of C-algebras one can construct from a shift of finite type. I will discuss properties of these C-algebras such as rational Poincare duality and rational isomorphism. Rationalizing shifts of finite type - Part II
Tue, Feb. 24 1:20pm (MATH 3…	Homotopy Irina Bokova (Texas A&M) TBD
Wed, Feb. 25 2:10pm (Math350)	Math Phys Howy Jordan (CU Boulder) View Online:https://cuboulder.zoom.us/j/97049173677 The spectral theorem and projection valued measures II
Thu, Feb. 26 11:15am (MATH …	Algebraic Geometry Lior Alon (MIT) X Abstract: The Poisson summation formula tells us that a lattice and its dual lattice are related through Fourier transform: the Fourier transform of the counting measure of one is the counting measure of the other. The search for non-periodic analogues of Poisson summation—discrete sets whose Fourier transform is again a discrete measure—has appeared independently across number theory, harmonic analysis, and crystallography. In the physical setting, the Fourier transform of the counting measure of an atomic structure is exactly the diffraction pattern observed experimentally. The term quasicrystal refers to a non-periodic set whose diffraction is a pure point measure, and the discovery of such materials by Dan Shechtman in 1984 profoundly altered crystallography and led to a Nobel Prize. A major mystery that remained unresolved until very recently was whether one could find a quasicrystal whose Fourier transform is supported on a discrete (rather than merely countable) set. These objects are now called Fourier quasicrystals (FQs), and until 2020 only the trivial periodic examples were known. Kurasov and Sarnak constructed the first genuinely non-periodic one-dimensional FQ using Lee–Yang polynomials, multivariate polynomials whose zeroes avoid prescribed regions of the complex plane. In our recent work, we show that every one-dimensional Fourier quasicrystal arises from the Kurasov–Sarnak construction via Lee–Yang polynomials, yielding a complete classification in dimension one. We then extend this framework to all dimensions by introducing Lee–Yang varieties, high-codimension algebraic varieties whose geometric and analytic properties govern the Fourier structure of the associated quasicrystals. The talk will introduce Fourier quasicrystals, Lee–Yang polynomials, and Lee–Yang varieties, and explain the geometric mechanism of generating summation formulas from algebraic varieties and how it is related to real-rootedness of trigonometric equations. No prior background will be assumed. Joint work with Alex Cohen, Cynthia Vinzant, Mario Kummer, and Pavel Kurasov. Fourier Quasicrystals and Lee–Yang Varieties
Thu, Feb. 26 3:30pm (Math 3…	Probability Lior Alon (MIT) TBD
Wed, Mar. 4 2:10pm (Math350)	Math Phys Markus J. Pflaum (CU Boulder) View Online:https://cuboulder.zoom.us/j/97049173677 TBA
Thu, Mar. 26 2:30pm (MATH 3…	Functional Analysis Karen Strung (Institute of Mathematics of the Czech Academy of Sciences) TBD Sponsored by the National Science Foundation
Thu, Mar. 26 3:35pm (MATH 3…	Probability Andrew Campbell (ISTA) TBD
Mon, Mar. 30 3pm (Kitt Cent…	DeLong Guoliang Yu (Texas AM University) View Online:https://cuboulder.zoom.us/j/97834671785 TBA General Audience talk Sponsored by the Meyer Fund
Wed, Apr. 1 3pm (Kitt Cent…	DeLong Guoliang Yu (Texas A&M University) View Online:https://cuboulder.zoom.us/j/97834671785 TBA Colloquium talk Sponsored by the Meyer Fund
Tue, Apr. 7 2:30pm (MATH 3…	Lie Theory J. Carlos Martínez Mori (University of Colorado Denver) TBD
Wed, Apr. 22 2:10pm (Math350)	Math Phys Mudassir Moosa (CU Boulder Physics) TBA
Thu, Apr. 23 2:30pm (MATH 3…	Functional Analysis J. Quigg (Arizona State University) TBA Sponsored by the Meyer Fund
Thu, Apr. 23 2:30pm (MATH 3…	Functional Analysis Roberto Hernandez Palomares (University of Waterloo) TBD Sponsored by the Meyer Fund
Tue, Apr. 28 2:30pm (MATH 3…	Lie Theory Sarah Brauner (Brown University) TBD

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