Nonabelian basechange theorems and étale homotopy theory

Haine, Peter J. and Holzschuh, Tim and Wolf, Sebastian (2024) Nonabelian basechange theorems and étale homotopy theory. JOURNAL OF TOPOLOGY, 17 (4): e70009. ISSN 1753-8416, 1753-8424

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Abstract

This paper has two main goals. First, we prove nonabelian refinements of basechange theorems in & eacute;tale cohomology (i.e., prove analogues of the classical statements for sheaves of spaces). Second, we apply these theorems to prove a number of results about the & eacute;tale homotopy type. Specifically, we prove nonabelian refinements of the smooth basechange theorem, Huber-Gabber affine analogue of the proper basechange theorem, and Fujiwara-Gabber rigidity theorem. Our methods also recover Chough's nonabelian refinement of the proper basechange theorem. Transporting an argument of Bhatt-Mathew to the nonabelian setting, we apply nonabelian proper basechange to show that the profinite & eacute;tale homotopy type satisfies arc-descent. Using nonabelian smooth and proper basechange and descent, we give rather soft proofs of a number of K & uuml;nneth formulas for the & eacute;tale homotopy type.

Item Type: Article
Uncontrolled Keywords: DESCENT; RAMIFICATION; GEOMETRY
Subjects: 500 Science > 510 Mathematics
Divisions: Mathematics
Depositing User: Dr. Gernot Deinzer
Date Deposited: 09 Dec 2025 07:04
Last Modified: 09 Dec 2025 07:04
URI: https://pred.uni-regensburg.de/id/eprint/64584

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