Calendar
- 29October 29, 2023No events
- 30October 30, 2023
CMSA Colloquium: Homotopy categories of rings: Some properties and consequences in module categories
20 Garden Street, Cambridge, MA 02138Given a non-necessarily commutative ring with unit and an additive subcategory of the category of right modules, one can consider complexes of modules in the subcategory and the corresponding homotopy category. Sometimes, these homotopy categories are the first step in studying other (algebraic) homotopy categories, such as those associated to a scheme. To study these categories, one can use results from the category of modules or the category of complexes. In the first part of the talk, we will see how some results of homotopy categories of complexes extend to homotopy categories of N-complexes, for a natural number N greater than or equal to 2, using some techniques from module categories, such us the deconstruction of a class of modules.
Another approximation is to use other methods for studying homotopy categories, like those coming from triangulated categories. In some cases, the results obtained in homotopy categories imply some consequences in the category of modules. In the second part of the talk, we will see how to prove the existence of Gorenstein-projective precovers for some specific rings using this approach.
- 31October 31, 2023
Harvard-MIT Algebraic Geometry Seminar: Singularities in mixed characteristic via the Riemann-Hilbert correspondence
1 Oxford Street, Cambridge, MA 02138 USAIn my talk, I will start by reviewing how various properties of characteristic zero singularities can be understood topologically by ways of the Riemann-Hilbert correspondence. After that, I will explain how similar ideas can be applied in the study of mixed characteristic singularities. This is based on a joint work (in progress) with Bhargav Bhatt, Linquan Ma, Zsolt Patakfalvi, Karl Schwede, Kevin Tucker, and Joe Waldron.
For more information, please see https://researchseminars.org/seminar/harvard-mit-ag-seminar
- 01November 1, 2023
Number Theory Seminar: The limit multiplicities and von Neumann dimensions
1 Oxford Street, Cambridge, MA 02138 USAGiven an arithmetic subgroup Γ in a semi-simple Lie group G, the multiplicity of an irreducible representation of G in L^2(Γ\G) is unknown in general.
We observe the multiplicity of any discrete series representation pi of SL (2, R) in L^2 (Γ(n)\SL (2, R)) is close to the von Neumann dimension of pi over the group algebra of Γ(n).
We extend this result to other Lie groups and bounded families of irreducible representations of them.
By applying the trace formulas, we show the multiplicities are exactly the von Neumann dimensions if we take certain towers of descending lattices in some Lie groups.Informal Seminar on Dynamics, Geometry and Moduli Spaces: The 3D dimer model
Please see website for more details: www.math.harvard.edu/~ctm/sem.
Richard P. Stanley Seminar in Combinatorics: Topology of moduli spaces via combinatorics
Deligne connects the weight-zero compactly supported cohomology of a moduli space to the combinatorics of its compactifications. This gives a method for using combinatorics to compute a piece of the cohomology of a moduli space. In this talk, we discuss this method for the cases of the moduli space of abelian varieties and the moduli space of n-marked hyperelliptic curves.
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For more info, see https://math.mit.edu/combin/
Open Neighborhood Seminar: How to Build a Random Surface
1 Oxford Street, Cambridge, MA 02138 USAThe theory of “random surfaces” has emerged in recent decades as a significant field of mathematics, lying somehow at the interface between geometry, probability, combinatorics, analysis and mathematical physics. Just as “Brownian motion” is a special kind of random path, there is a similarly special kind of random surface.
Random surfaces are often motivated by physics: statistical physics, string theory, quantum field theory, and so forth. They have also been independently studied by mathematicians working in random matrix theory and enumerative graph theory. But even without that motivation, one may be drawn to wonder what a “typical” two-dimensional manifold looks like, or how one can make sense of that question.
I will give an overview of what this theory is about, including many computer simulations and illustrations. In particular, I will discuss the so-called Liouville quantum gravity surfaces, and explain how they are approximated by discrete random surfaces called random planar maps.
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https://people.math.harvard.edu/~gammage/ons/
- 02November 2, 2023
CMSA Joint Quantum Matter in Mathematics and Physics and Topological Quantum Matter Seminar: Landscape of quantum phases in quantum materials
20 Garden Street, Cambridge, MA 02138A central goal of condensed matter physics is to understand which quantum phases of matter can emerge in a quantum material. For this purpose, one should be able to not only describe the quantum phases using some effective field theories, but also capture the important microscopic information of the material via mathematical formulation. In this talk, I will present a framework to classify quantum phases in quantum materials, where the microscopic information of a material is encoded in its quantum anomaly. I will talk about the application of this framework to classify various exotic quantum phases of matter in different lattice systems. Using our framework, we have obtained many results unexpected from the previous literature.
Zoom: https://harvard.zoom.us/j/977347126
Password: cmsa - 03November 3, 2023
Richard P. Stanley Seminar in Combinatorics: Tiling, Sodoku, Domino, and Decidability
Translational tiling is a covering of a space (such as Euclidean space) using translated copies of one building block, called a “translational tile”, without any positive measure overlaps.
Can we determine whether a given set is a translational tile? Does any translational tile admit a periodic tiling? A well known argument shows that these two questions are closely related. In the talk, we will discuss this relation and present some new developments, joint with Terence Tao, establishing answers to both questions.===============================
For more info, see https://math.mit.edu/combin/
- 04November 4, 2023No events