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        "datetime_modified":"20261101T133035",
        "datetime_start":"20261102T160000",
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        "date_end":"2026-11-02",
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        "event_title":"How plabic graphs describe weakly separated collections",
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        "combined_title":"How plabic graphs describe weakly separated collections: Veronica Lang",
        "event_subtitle":"Veronica Lang",
        "event_type":"Workshop \/ Seminar",
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        "description":"Two k-element subsets I,J of {1,2,\u2026,n} are weakly separated if the sets I\\J and J\\I (when drawn on a circle with vertices 1,2,\u2026,n) can be separated by a chord. A maximal weakly separated collection is a set of pairwise weakly-separated k-element subsets of {1,2,\u2026,n} that is not contained in any larger set with this property. This definition gives rise to natural combinatorial questions: How big is a maximal weakly separated collection? How many are there? How are they related to each other?\n\nI will outline how Oh, Posknikov, Speyer answered most of these questions via a bijection between maximal weakly separated collections in a positroid and move-equivalent plabic graphs. Along the way, we\u2019ll meet some fun combinatorial objects related to plabic graphs including bounded affine permutations, Grassmann necklaces, positroids, and plabic tilings.",
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                "group_name":"Student Combinatorics Seminar - Department of Mathematics",
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    {
        "datetime_modified":"20261102T113259",
        "datetime_start":"20261102T160000",
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        "has_end_time":1,
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        "time_zone":"America\/Detroit",
        "event_title":"ISRMT Seminar: On Hirota's discrete KP equation - from geometry to multiple bi-orthogonal polynomials",
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        "combined_title":"ISRMT Seminar: On Hirota's discrete KP equation - from geometry to multiple bi-orthogonal polynomials: Adam Doliwa (University of Warmia and Mazury in Olsztyn)",
        "event_subtitle":"Adam Doliwa (University of Warmia and Mazury in Olsztyn)",
        "event_type":"Workshop \/ Seminar",
        "event_type_id":"21",
        "description":"Abstract: We generalize the well known connection between the Toda lattice equation, Pade approximants and orthogonal polynomials to the level of the Hirota system. We first present incidence geometric meaning of the multidimensional consistency of the system and its relation to Zamoldchikov's tetrahedron equation. Then we show how Hermite-Pade approximants and multiple orthogonal polynomials provide certain solutions to the Hirota system and its linear problem. Finally, we extend the construction to the case of bi-moments and quasi-determinants.",
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                "guid":"153397-21915803@events.umich.edu",
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        "tags":["Mathematics"],
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             {
                "group_name":"Integrable Systems and Random Matrix Theory Seminar - Department of Mathematics",
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