Beilinson--Lichtenbaum phenomenon for motivic cohomology

Fuente: arXiv
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Main Authors: Bouis, Tess, Kundu, Arnab
Format: Preprint
Published: 2025
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_version_ 1866912425192718336
author Bouis, Tess
Kundu, Arnab
author_facet Bouis, Tess
Kundu, Arnab
contents The goal of this paper is to study non-$\mathbb{A}^1$-invariant motivic cohomology, recently defined by Elmanto, Morrow, and the first-named author, for smooth schemes over possibly non-discrete valuation rings. We establish that the cycle class map from $p$-adic motivic cohomology to a suitable truncation of Bhatt--Lurie's syntomic cohomology is an isomorphism, thereby verifying the Beilinson--Lichtenbaum conjecture in this generality. As a consequence, we prove that this motivic cohomology integrally recovers the classical definition of motivic cohomology in terms of Bloch's cycle complexes, whenever the latter is defined. Over perfectoid rings, we show that this cohomology theory is actually $\mathbb{A}^1$-invariant, thus partially answering a question of Antieau--Mathew--Morrow. The key ingredient in our approach is a version of Gabber's presentation lemma applicable in mixed characteristic, non-noetherian settings.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09910
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Beilinson--Lichtenbaum phenomenon for motivic cohomology
Bouis, Tess
Kundu, Arnab
Algebraic Geometry
K-Theory and Homology
Number Theory
The goal of this paper is to study non-$\mathbb{A}^1$-invariant motivic cohomology, recently defined by Elmanto, Morrow, and the first-named author, for smooth schemes over possibly non-discrete valuation rings. We establish that the cycle class map from $p$-adic motivic cohomology to a suitable truncation of Bhatt--Lurie's syntomic cohomology is an isomorphism, thereby verifying the Beilinson--Lichtenbaum conjecture in this generality. As a consequence, we prove that this motivic cohomology integrally recovers the classical definition of motivic cohomology in terms of Bloch's cycle complexes, whenever the latter is defined. Over perfectoid rings, we show that this cohomology theory is actually $\mathbb{A}^1$-invariant, thus partially answering a question of Antieau--Mathew--Morrow. The key ingredient in our approach is a version of Gabber's presentation lemma applicable in mixed characteristic, non-noetherian settings.
title Beilinson--Lichtenbaum phenomenon for motivic cohomology
topic Algebraic Geometry
K-Theory and Homology
Number Theory
url https://arxiv.org/abs/2506.09910