Splitting vector bundles over real algebraic varieties

Fuente: arXiv
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Main Authors: Asok, Aravind, Fasel, Jean, Lerbet, Samuel
Format: Preprint
Published: 2025
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author Asok, Aravind
Fasel, Jean
Lerbet, Samuel
author_facet Asok, Aravind
Fasel, Jean
Lerbet, Samuel
contents Suppose $X$ is a smooth affine real variety and $\mathscr{E}$ is a vector bundle over $X$. We analyze the problem of splitting off a free rank one summand from $\mathscr{E}$ in corank $0$ and $1$. The problem in corank $0$ can be viewed as the search for a real analog of Murthy's celebrating splitting theorem in the algebraically closed case: to wit, beyond the vanishing of the top Chern class in Chow theory, are the obstructions to splitting ``purely topological''? In a sense, the answer in this case is yes, and we give a proof, using motivic techniques, of a mild extension of the results of Bhatwadekar-Sridharan and Bhatwadekar-Das-Mandal. In corank $1$, in the algebraically closed situation, Murthy's splitting conjecture (now a theorem in characteristic $0$) predicts that the vanishing of the top Chern class in Chow theory is the only obstruction to splitting off a free rank $1$ summand, and we can search for a suitable ``real'' analog of this assertion. We observe that several natural guesses for a ``real'' analog of Murthy's splitting conjecture cannot be true, i.e., that the situation over the real numbers is rather complicated.
format Preprint
id arxiv_https___arxiv_org_abs_2511_15616
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Splitting vector bundles over real algebraic varieties
Asok, Aravind
Fasel, Jean
Lerbet, Samuel
Algebraic Geometry
Commutative Algebra
Algebraic Topology
K-Theory and Homology
14F42 (Primary) 14F25, 13C10, 55R25 (Secondary)
Suppose $X$ is a smooth affine real variety and $\mathscr{E}$ is a vector bundle over $X$. We analyze the problem of splitting off a free rank one summand from $\mathscr{E}$ in corank $0$ and $1$. The problem in corank $0$ can be viewed as the search for a real analog of Murthy's celebrating splitting theorem in the algebraically closed case: to wit, beyond the vanishing of the top Chern class in Chow theory, are the obstructions to splitting ``purely topological''? In a sense, the answer in this case is yes, and we give a proof, using motivic techniques, of a mild extension of the results of Bhatwadekar-Sridharan and Bhatwadekar-Das-Mandal. In corank $1$, in the algebraically closed situation, Murthy's splitting conjecture (now a theorem in characteristic $0$) predicts that the vanishing of the top Chern class in Chow theory is the only obstruction to splitting off a free rank $1$ summand, and we can search for a suitable ``real'' analog of this assertion. We observe that several natural guesses for a ``real'' analog of Murthy's splitting conjecture cannot be true, i.e., that the situation over the real numbers is rather complicated.
title Splitting vector bundles over real algebraic varieties
topic Algebraic Geometry
Commutative Algebra
Algebraic Topology
K-Theory and Homology
14F42 (Primary) 14F25, 13C10, 55R25 (Secondary)
url https://arxiv.org/abs/2511.15616