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BIMSA AG Seminar
BIMSA AG Seminar
The equivariant Milnor-Witt motive of moduli space of curves
The equivariant Milnor-Witt motive of moduli space of curves
Organizers
Speaker
Time
Thursday, June 18, 2026 3:00 PM - 4:00 PM
Venue
A6-101
Online
Zoom 518 868 7656
(BIMSA)
Abstract
Grothendieck’s category of Chow motives, built from smooth projective varieties, was designed so that every Weil cohomology functor factors through it. By extending this framework to non-projective smooth varieties—via compactification and desingularization—we arrive at Voevodsky’s category of mixed motives, which provides a natural setting for motivic cohomology. Around 2020, an even more refined framework emerged: the category of Milnor-Witt motives. This category captures the quadratic information of base fields and sits much closer to the motivic stable homotopy category.
In this talk, we present a concise decomposition of the equivariant Milnor-Witt motive for the moduli space of elliptic curves with two marked points. By combining this decomposition with the work of Lorenzo and Mantovani, we can fully determine the quadratic refined intersection ring (the Chow-Witt ring) of this moduli space.
In this talk, we present a concise decomposition of the equivariant Milnor-Witt motive for the moduli space of elliptic curves with two marked points. By combining this decomposition with the work of Lorenzo and Mantovani, we can fully determine the quadratic refined intersection ring (the Chow-Witt ring) of this moduli space.
Speaker Intro
Nanjun Yang got his doctor and master degree in University of Grenoble-Alpes, advised by Jean Fasel, and bachelor degree in Beihang University. Then he became a postdoc in YMSC. Currently he is a assistant professor in BIMSA. His research interest is the Chow-Witt group of algebraic varieties, with publications on journals such as Camb. J. Math and Ann. K-Theory.