Endomorphisms of the Cohomology Algebra of the Even Orthogonal Grassmannian

Fuente: arXiv
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Main Authors: Goswami, Arnab, Sarkar, Swagata
Format: Preprint
Published: 2025
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author Goswami, Arnab
Sarkar, Swagata
author_facet Goswami, Arnab
Sarkar, Swagata
contents Let $M_{n,k}$ denote the even orthogonal Grassmanian, $SO(2n) / (U(k) \times SO(2n-2k) )$. We study endomorphisms of the rational cohomology algebra of $M_{n,k}$. We prove that an endomorphism of the rational cohomology algebra of $M_{n,k}$, which maps all the Chern classes of the canonical $k$-plane bundle over $M_{n,k}$ to zero, or maps all the Pontrjagin classes of the canonical, real, oriented $(2n-2k)$-plane bundle over $M_{n,k}$ to zero, is the zero endomorphism. Additionally, we prove that if an endomorphism of the rational cohomology algebra of $M_{n,k}$ vanishes on $H^{2}(M_{n,k}; \mathbb{Q})$, and admits a splitting, then the splitting equals zero.
format Preprint
id arxiv_https___arxiv_org_abs_2509_09363
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Endomorphisms of the Cohomology Algebra of the Even Orthogonal Grassmannian
Goswami, Arnab
Sarkar, Swagata
Algebraic Topology
Primary: 57T15, 14M17, 55M99, Secondary: 14M15, 55S99
Let $M_{n,k}$ denote the even orthogonal Grassmanian, $SO(2n) / (U(k) \times SO(2n-2k) )$. We study endomorphisms of the rational cohomology algebra of $M_{n,k}$. We prove that an endomorphism of the rational cohomology algebra of $M_{n,k}$, which maps all the Chern classes of the canonical $k$-plane bundle over $M_{n,k}$ to zero, or maps all the Pontrjagin classes of the canonical, real, oriented $(2n-2k)$-plane bundle over $M_{n,k}$ to zero, is the zero endomorphism. Additionally, we prove that if an endomorphism of the rational cohomology algebra of $M_{n,k}$ vanishes on $H^{2}(M_{n,k}; \mathbb{Q})$, and admits a splitting, then the splitting equals zero.
title Endomorphisms of the Cohomology Algebra of the Even Orthogonal Grassmannian
topic Algebraic Topology
Primary: 57T15, 14M17, 55M99, Secondary: 14M15, 55S99
url https://arxiv.org/abs/2509.09363