On the Calegari-Venkatesh conjecture connecting modular forms spaces and algebraic K-Theory

Fuente: arXiv
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Main Authors: Rahm, Alexander D., Emiliano, Torti
Format: Preprint
Published: 2025
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author Rahm, Alexander D.
Emiliano, Torti
author_facet Rahm, Alexander D.
Emiliano, Torti
contents Calegari and Venkatesh did construct, modulo small torsion, a surjection from the degree 2 homology of the rank 2 projective general linear group over a ring of algebraic integers (of odd class number, and with enough embeddings) to the 2nd algebraic K-group of that ring. They asked whether this surjection becomes an isomorphism when passing to the quotient modulo the Eisenstein ideal on the left hand side. We provide a new method (together with numerical examples) to lift elements in the opposite direction, enabled by a theorem in a more general setting, where we exploit a connection between the algebraic K-groups and the Steinberg homology groups.
format Preprint
id arxiv_https___arxiv_org_abs_2504_00687
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Calegari-Venkatesh conjecture connecting modular forms spaces and algebraic K-Theory
Rahm, Alexander D.
Emiliano, Torti
K-Theory and Homology
Calegari and Venkatesh did construct, modulo small torsion, a surjection from the degree 2 homology of the rank 2 projective general linear group over a ring of algebraic integers (of odd class number, and with enough embeddings) to the 2nd algebraic K-group of that ring. They asked whether this surjection becomes an isomorphism when passing to the quotient modulo the Eisenstein ideal on the left hand side. We provide a new method (together with numerical examples) to lift elements in the opposite direction, enabled by a theorem in a more general setting, where we exploit a connection between the algebraic K-groups and the Steinberg homology groups.
title On the Calegari-Venkatesh conjecture connecting modular forms spaces and algebraic K-Theory
topic K-Theory and Homology
url https://arxiv.org/abs/2504.00687