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Events happening on January 21, 2020

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Jan. 21, 2020 1pm (MATH 220)	Grad Algebra/Logic Dmitriy Zhuk (Moscow State University) Quantified Constraint Satisfaction Problems Sponsored by the Meyer Fund
Jan. 21, 2020 2pm (MATH 220)	Alexandr Kazda (Charles University Prague) The category of valued relational structures Sponsored by the Meyer Fund
Jan. 21, 2020 2pm (MATH 350)	Functional Analysis Karen Strung (Czech Academy of Sciences, Prague) X Given a Hilbert C-correspondence over C(X), one can construct the associated Cuntz-Pimsner algebra. In the case that the correspondence is full, nonperiodic, and minimal, the resulting C-algebra is simple and unital. An example of such a correspondence is obtained by taking the right Hilbert C(X)-module of continuous sections of a vector bundle over X and twisting the left multiplication by a minimal homeomorphism. As is the case of crossed products by minimal homeomorphisms, one can identify "orbit-breaking" C-subalgebras. In this talk I will discuss these Cuntz--Pimsner C-algebras and their orbit-breaking subalgebras, their relationship to one another, and when they can be classified by Elliott invariants. This is joint work with Adamo, Archey, Forough, Georgescu, Jeong and Viola. Simple constructions from Hilbert C(X)-correspondences Sponsored by the Meyer Fund
Jan. 21, 2020 4pm (MATH350)	Topology Hessel Posthuma (Amsterdam) X In this talk I will explain how to define so-called �higher genera� for a proper cocompact action of a Lie group satisfying some additional assumptions. These higher genera are numbers, whose definition is inspired by index theory for Dirac type operators in Noncommutative Geometry, and generalize the signature and A-hat genus for compact manifolds. The main theorem states that the higher signatures are equivariant homotopy invariants and that vanishing of the higher A-hat numbers is a necessary condition for the existence of an invariant spin structure together with a metric of positive scalar curvature. This talk is based on joint work with P. Piazza. Higher genera for proper action of Lie groups Sponsored by the Meyer Fund
Jan. 21, 2020 10pm (Math 350)	Noncomm Geometry Vladimir Baranovsky (University of California, Irvine) X For an algebraic or holomorphic symplectic variety M with a chosen deformation quantization of functions we consider a coherent sheaf F and try to find its deformation quantization as well. It turns out that existence of such quantization imposes nontrivial conditions on the Chern Character of F. These will be derived in the talk from the Algebraic Index Theorem. Chern character of quantizable sheaves
Jan. 21, 2020 11pm (MATH 220)	Functional Analysis Elizabeth Gillaspy (University of Montana) X Higher-rank graphs (k-graphs) are a combinatorial model for C-algebras; indeed, much of the structure of k-graph C-algebras is encoded in the underlying combinatorial data of the k-graph. However, different k-graphs can give rise to isomorphic or Morita equivalent C-algebras. In this talk, we present several ways to modify the structure of a k-graph which preserve the Morita equivalence class of the associated C-algebra. Our constructions are inspired by the analogous work for graph C*-algebras of Bates and Pask, as well as by the textile system approach to describing k-graphs. This is joint work with C. Eckhardt, K. Fieldhouse, D. Gent, I. Gonzales, and D. Pask. Moves on higher-rank graphs preserving Morita equivalence Sponsored by the Meyer Fund

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