$University of Colorado Boulder$

Search

Algebraic Geometry Algebra/Logic DeLong Diversity Functional Analysis Geometry/Analysis Init Conditions Kempner Lie Theory MathClub Math Phys Noncomm Geometry Number Theory Probability Rep Theory Grad Student Seminar Thesis Defenses Topology Ulam Math Edu

Events happening on April 20, 2021

Return to this week

Print these events

Apr. 20, 2021 10am (via Zoom)	Geometry/Analysis Teemu Saksala (North Carolina Stat University) X Consider the geometric inverse problem: There is a set of delta-sources in spacetime that emit waves travelling at unit speed. If we know all the arrival times at the boundary cylinder of the spacetime, can we reconstruct the space, a Riemannian manifold with boundary? With a finite set of sources we can only hope to get an approximate reconstruction, and we indeed provide a discrete metric approximation to the manifold with explicit data-driven error bounds when the manifold is simple. This is the geometrization of a seismological inverse problem where we measure the arrival times on the surface of waves from an unknown number of unknown interior microseismic events at unknown times. The closeness of two metric spaces with a marked boundary is measured by a labeled Gromov--Hausdorff distance. If measurements are done for infinite time and spatially dense sources, our construction produces the true Riemannian manifold and the finite-time approximations converge to it in the metric sense. This talk is based on a joint work with Maarten V. de Hoop, Joonas Ilmavirta and Matti Lassas Stable reconstruction of simple Riemannian manifolds from unknown interior sources
Apr. 20, 2021 1pm (Zoom)	Ross Willard (University of Waterloo) X This is a progress report on an exploration of Isaev's algebras and their cousins. Isaev's algebras were the first, and remain the only, known examples of inherently nonfinitely based finite algebras in Maltsev varieties. In this talk I will describe a class of finite algebras containing Isaev's algebras, and explain some basic tools that we have developed to help determine which of these algebras are inherently nonfinitely based. At the moment we are only able to apply these tools to Isaev's algebras themselves, but that won’t stop me from filling the 50-minute time slot which I have been offered! This is joint work with Emily Carlson, Mehul Gupta and George McNulty. Inherently nonfinitely based nonassociative algebras
Apr. 20, 2021 1:30pm (https:…	Diversity Ysatiz M. Piñero (Center for Inclusion and Social Change) X Co-facilitated by CISC staff and the peer education team, this interactive 90-minute training is designed for students on the CU Boulder campus. During the training, participants will engage in small and large group discussions to help identify examples of sexism in their lives or in an institution they participate in. They will also learn strategies for interrupting sexism. https://cuboulder.zoom.us/j/99247389611 Recognizing & Interrupting Sexism
Apr. 20, 2021 2pm (MATH 350)	Lie Theory Riccardo Biagioli (University of Bologna) X The Temperley-Lieb algebra is a well studied finite dimensional associative algebra : it can be realized as a diagram algebra and it has a basis indexed by the fully commutative elements in the Coxeter group of type A. A few years ago, Dana Ernst introduced an elegant generalization of such diagrammatic representation for the generalized Temperley-Lieb algebra of type affine C. The proof that such representation is faithful is quite involved and the same author wonders if an easier proof exists. In this talk, we present a new combinatorial way to describe Ernst’s algebra homomorphism, from which injectivity and subjectivity follow more easily. Our results are based on a recent classification of fully commutative elements of type affine C in terms of heaps of pieces, and on certain operations that we define on such heaps. This is a joint work with Giuliana Fatabbi and Gabriele Calussi. Temperley-Lieb algebra and fully commutative elements in type affine C

Return to the top of the page