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        "event_title":"On hypoellipticity of degenerate operators in testing and detection problems",
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        "combined_title":"On hypoellipticity of degenerate operators in testing and detection problems: Yuqiong Wang, UM.",
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        "description":"We study a class of degenerate diffusion generators that arise in sequential testing and quickest detection problems with partial information. The observation process is driven by k independent Brownian motions, while the hidden state takes n+1 values with k<n. By moving to the posterior likelihood coordinates, we analyze the H\u00f6mander's condition of the operator both without state switching (testing) and with switching (detection). We characterize the cases where the operator is hypoelliptic for the former, give two different sufficient conditions for the latter, and discuss their consequences.\r\n\r\nJoint work with Erhan Bayraktar",
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        "datetime_modified":"20260131T210649",
        "datetime_start":"20260204T160000",
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        "date_start":"2026-02-04",
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        "event_title":"RTG SEMINAR GEOMETRY TOPOLOGY DYNAMICS:  Arithmeticity, superrigidity, and totally geodesic submanifolds",
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        "combined_title":"RTG SEMINAR GEOMETRY TOPOLOGY DYNAMICS:  Arithmeticity, superrigidity, and totally geodesic submanifolds: Alex Maldague (Rice)",
        "event_subtitle":"Alex Maldague (Rice)",
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        "description":"In 2018, Bader and Furman extended Margulis' higher-rank superrigidity theorem using the notion of algebraic representations of ergodic actions, abbreviated AREA. The idea now is to apply the AREA machinery in the rank-1 setting, where superrigidity remains a mysterious phenomenon. This talk will serve as a preview for my talk in the Geometry seminar, where I will discuss recent progress in this direction. In particular, I will review important elements of Margulis' original proof of superrigidity and provide some context for the recent work of Bader-Fisher-Miller-Stover on the arithmeticity of finite-volume hyperbolic manifolds with infinitely many maximal totally geodesic submanifolds.",
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