Unipotent homotopy theory of schemes

Fuente: arXiv
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Main Authors: Mondal, Shubhodip, Reinecke, Emanuel
Format: Preprint
Published: 2023
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author Mondal, Shubhodip
Reinecke, Emanuel
author_facet Mondal, Shubhodip
Reinecke, Emanuel
contents Building on Toën's work on affine stacks, we develop a certain homotopy theory for schemes, which we call "unipotent homotopy theory." Over a field of characteristic $p>0$, we prove that the unipotent homotopy group schemes $π_i^{\mathrm{U}}(\,\cdot\,)$ introduced in our paper recover the unipotent Nori fundamental group scheme, the $p$-adic étale homotopy groups, as well as certain formal groups introduced by Artin and Mazur. We prove a version of the classical Freudenthal suspension theorem as well as a profiniteness theorem for unipotent homotopy group schemes. We also introduce the notion of a formal sphere and use it to show that for Calabi-Yau varieties of dimension $n$, the group schemes $π_i^{\mathrm{U}}(\,\cdot\,)$ are derived invariants for all $i \ge 0$; the case $i=n$ is related to recent work of Antieau and Bragg involving topological Hochschild homology. Using the unipotent homotopy group schemes, we establish a correspondence between formal Lie groups and certain higher algebraic structures.
format Preprint
id arxiv_https___arxiv_org_abs_2302_10703
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Unipotent homotopy theory of schemes
Mondal, Shubhodip
Reinecke, Emanuel
Algebraic Geometry
Algebraic Topology
14F35, 14L05, 55P99, 18F20
Building on Toën's work on affine stacks, we develop a certain homotopy theory for schemes, which we call "unipotent homotopy theory." Over a field of characteristic $p>0$, we prove that the unipotent homotopy group schemes $π_i^{\mathrm{U}}(\,\cdot\,)$ introduced in our paper recover the unipotent Nori fundamental group scheme, the $p$-adic étale homotopy groups, as well as certain formal groups introduced by Artin and Mazur. We prove a version of the classical Freudenthal suspension theorem as well as a profiniteness theorem for unipotent homotopy group schemes. We also introduce the notion of a formal sphere and use it to show that for Calabi-Yau varieties of dimension $n$, the group schemes $π_i^{\mathrm{U}}(\,\cdot\,)$ are derived invariants for all $i \ge 0$; the case $i=n$ is related to recent work of Antieau and Bragg involving topological Hochschild homology. Using the unipotent homotopy group schemes, we establish a correspondence between formal Lie groups and certain higher algebraic structures.
title Unipotent homotopy theory of schemes
topic Algebraic Geometry
Algebraic Topology
14F35, 14L05, 55P99, 18F20
url https://arxiv.org/abs/2302.10703