19–23 Aug 2024
IBS Science Culture Center
Asia/Seoul timezone

Representations on the cohomology of the moduli space of pointed rational curves, permutation representations and log concavity

22 Aug 2024, 10:55
25m
S236 (IBS Science Culture Center)

S236

IBS Science Culture Center

Daejeon, Yuseong District, Expo-ro, 55 과학문화센터
Presentation (25 min)

Speaker

Donggun Lee (Institute for Basic Science)

Description

The Chow ring of the graphical matroid of the complete graph with n-1 vertices (with respect to the minimal building set) is isomorphic to that of the moduli space of n-pointed rational curves. Therefore, it is naturally a graded representation of the n-th symmetric group.

In this talk, we provide a closed-form formula for this representation, in terms of weighted rooted trees, which we introduce as combinatorial gadgets. Using this, we explore the positivity of this representation as a permutation representation, and the asymptotic log concavity of the multiplicities of the trivial representation. We will also discuss about the multiplicities of the other irreducible representations.

Based on joint works with Jinwon Choi and Young-Hoon Kiem.

Primary author

Donggun Lee (Institute for Basic Science)

Co-authors

Presentation materials

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