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Events happening on September 18, 2018

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Sep. 18, 2018 10am (MATH 350)	Geometry/Analysis Yuhao Hu (University of Colorado, Boulder) Geometry of Backlund transformations Sponsored by the Meyer Fund
Sep. 18, 2018 1pm (MATH 220)	Peter Mayr X We discuss several classical reductions between CSPs over finite constraint languages. In particular we show that each constraint language may be replaced by the singleton expansion of its core. Further the complexity of CSP(Gamma) is determined by the variety generated by its polymorphism algebra. CSP reductions
Sep. 18, 2018 2pm (MATH 220)	Agnes Szendrei (CU Boulder) Overview of the Malliaris--Shelah paper, Part 2
Sep. 18, 2018 2pm (Math 350)	Lie Theory Julianne Rainbolt (Saint Louis University) X Let $\tilde{G}$ denote a connected reductive algebraic group defined over an algebraically closed field of characteristic $p > 0$ . Let $F : \tilde{G} \to \tilde{G}$ be a Frobenius endomorphism. Let $G$ be the finite group of Lie type which is the fixed points of $F$ . Let $B$ be an $F$ -stable Borel subgroup of $\tilde{G}$ and let $T$ be an $F$ -stable maximal torus of $\tilde{G}$ contained in $B$ . Let $N = NG(T)$ . Denote the Weyl group of $G$ by $W = NF/TF$ . The element $\overset{\cdot}{w}$ will denote a preimage of $w ∈ W$ with respect to the natural surjection from $N^{F}$ to $W$ . The double cosets $B^{F} \overset{\cdot}{w} B^{F}$ are called the Bruhat cells of $G$ . An element $x ∈ G$ is called regular if the dimension of its centralizer is minimal. In this talk, we will discuss necessary and sufficient conditions for Bruhat cells to contain only regular elements. Furthermore, we will investigate Bruhat cells that contain both regular and nonregular elements but have cosets consisting entirely of regular elements. Cosets and Double Cosets Containing only Regular Elements Sponsored by the Meyer Fund

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