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Guillaume Laplante-Anfossi: Postdoc day, Seminar 3: Diagonals of polytopes and higher structures

Time: Fri 2022-02-25 15.10 - 15.40

Location: Institut Mittag-Leffler, Seminar Hall Kuskvillan and Zoom

Video link: Meeting ID: 921 756 1880

Lecturer: Guillaume Laplante-Anfossi (Université Sorbonne Paris Nord)

Abstract: The set-theoretic diagonal of a polytope has the crippling defect of not being cellular: its image is not a union of cells. One is thus looking for a cellular approximation to the diagonal. Finding such an approximation in the case of the simplices and the cubes is of fundamental importance in algebraic topology: it allows one to define the cup product in cohomology. I will present a general method, coming from the theory of fiber polytopes of Billera and Sturmfels, which permits to solve this problem for any family of polytopes. I will then sketch how this machinery, applied to new families of polytopes, gives us the tools to define higher algebraic objects such as the tensor product of homotopy operads or a functorial tensor product of A-infinity categories.