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Events for December 2024 – April 2025

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Thu, Mar. 13 5pm	Functional Analysis Jordan Watts (University of Central Michigan) TBA
Tue, Dec. 3 1:15pm (Math 3…	Functional Analysis Peter Haskell (Virginia Tech University) View Online:Zoom link to follow X Jeff Fox and I met in 1983. We were intrigued by Kasparov's elegant and powerful bivariant K-theory, and we dared hope it would allow us to use Jeff's background in representation theory and mine in topology to prove cases of the Baum-Connes and Connes-Kasparov conjectures. The depth of the challenges posed by those conjectures was greater than we first imagined, but, largely due to Jeff's knowledge of representation theory, we did make a contribution to the area. We also proved some representation-multiplicity index theorems for transversally elliptic operators. These results illustrated K-theory's ability to extract representation-theoretic integer-valued invariants from group C*-algebras. Other work we did involved index theory for singular spaces, pushing inspiration from Riemann-Roch theorems in directions that involved enough analysis to suggest roles for spectral invariants. I learned much mathematics and much about how to do mathematics from Jeff. Working with him, I got to know one of the kindest, most generous people I have ever met. My collaboration with Jeff Fox: Mathematical and personal connections formed as products of Kasparov's bivariant K-theory
Tue, Dec. 3 3:30pm (MATH 3…	Topology Alexander LaJeunesse TBD
Wed, Dec. 4 3:30pm (Math350)	Math Phys Andrew Doumont (CU Boulder) Gromov-Witten Invariants
Thu, Dec. 5 11:15am (MATH …	Algebraic Geometry Daniel Lyness TBA
Thu, Dec. 5 2pm (Zoom)	Algebraic Geometry Nicola Tarasca (Virginia Commonwealth University) View Online:https://cuboulder.zoom.us/j/97927772782 TBA
Thu, Dec. 5 2pm (Online)	Rep Theory Nicola Tarasca (Virginia Commonwealth University) View Online:https://cuboulder.zoom.us/j/97927772782 TBA
Thu, Dec. 5 2:30pm (MATH 3…	Functional Analysis Levi Lorenzo and Maggie Reardon (CU Boulder) X There will be two 25-minute talks. Abstract (Levi Lorenzo): K-theory is the generalized cohomology theory that has proven incredibly effective at classifying C- algebras. In this talk, we discuss its dual homology theory, K-homology. K-homology and K-theory admit a bilinear pairing to the integers, called the index pairing, which allows one to learn about K-theory using K-homology and vice versa. In general, this pairing is very difficult to compute; however, if a Calgebra admits a dense subalgebra on which its K-homology is finitely summable, Connes has equipped us with a more computable formula. Given a smooth manifold, M, of dimension n, the K-homology of is finitely summable on for In this way, the summability also sees the dimension of the manifold. It is natural to ask whether similar results hold in the noncommutative setting. Towards this end, Connes showed that the irrational rotation algebras have uniformly summable K-homology. The irrational rotation algebras are examples of crossed product algebras arising from minimal actions on a topological space. In my work, I study other noncommutative algebras and ask the same question. For example, we make the space a Cantor Set and examine the K-homology of crossed products arising from minimal actions on it. In this talk, we discuss progress in such directions. Abstract (Maggie Reardon): Matui’s HK-conjecture proposes a relationship between the homology groups of a nice enough groupoid and the $K$ -theory of the associated reduced $C$ -algebra. The conjecture is not true in general and there are a number of counterexamples. However, the conjecture holds for certain classes of groupoids including AF groupoids. Putnam introduced a new class of groupoids in the paper titled “Some classifiable groupoid $C$ -algebras with prescribed $K$ -theory”. These new groupoids are related to AF groupoids and this prompts a natural question: does this new class of groupoids satisfy the HK-conjecture? Finitely Summable K-homology and the HK-conjecture for certain groupoids constructed by Putnam
Fri, Dec. 6 10:10am (MATH …	Math Edu Rebecca Machen DBER
Wed, Dec. 11 4:45pm (MATH 3…	Grad Student Seminar Howy Jordan (CU Boulder) X TBD Stratified Spaces
Thu, Dec. 12 11:15am (MATH …	Algebraic Geometry Matthew Watson TBA
Thu, Dec. 12 2pm (Online)	Rep Theory Michael Lau (Université Laval) View Online:https://cuboulder.zoom.us/j/97927772782 TBA
Tue, Feb. 18 12pm (MATH 350)	Algebraic Geometry Mihnea Popa (Harvard) X TBD TBD Sponsored by the Meyer Fund
Tue, Mar. 11 12:10pm (MATH …	Kempner Edmund Harriss (University of Arkansas) TBA
Thu, Mar. 20 2:30pm (MATH 3…	Functional Analysis Laura Scull (Fort Lewis College) TBA
Fri, Apr. 25 2:30pm (MATH 3…	Geometry/Analysis Maja Taskovic (Emory University) TBA Sponsored by the Meyer Fund

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