A necessary condition for liftings of positive characteristic varieties with finite fundamental groups

Fuente: arXiv
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Auteurs principaux: Di, Ruida, Hu, Runjie, Zhang, Siqing
Format: Preprint
Publié: 2025
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author Di, Ruida
Hu, Runjie
Zhang, Siqing
author_facet Di, Ruida
Hu, Runjie
Zhang, Siqing
contents In this paper, we introduce a necessary condition for the existence of characteristic zero liftings of certain smooth, proper varieties in positive characteristic, using etale homotopy theory and Wall's finiteness obstruction. For a variety with finite etale fundamental group pi, we define a notion of mod-l finite dominatedness based on the F_l-chain complex of the universal cover of its l-profinite etale homotopy type. We prove that such a variety X can be lifted to characteristic zero only if the above chain complex of X is quasi-isomorphic to a bounded complex of finitely generated projective F_l[pi]-modules. To prove this result, we extend Wall's discussions of finiteness obstructions to l-profinite complete spaces with finite fundamental group.
format Preprint
id arxiv_https___arxiv_org_abs_2506_07914
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A necessary condition for liftings of positive characteristic varieties with finite fundamental groups
Di, Ruida
Hu, Runjie
Zhang, Siqing
Algebraic Topology
Algebraic Geometry
In this paper, we introduce a necessary condition for the existence of characteristic zero liftings of certain smooth, proper varieties in positive characteristic, using etale homotopy theory and Wall's finiteness obstruction. For a variety with finite etale fundamental group pi, we define a notion of mod-l finite dominatedness based on the F_l-chain complex of the universal cover of its l-profinite etale homotopy type. We prove that such a variety X can be lifted to characteristic zero only if the above chain complex of X is quasi-isomorphic to a bounded complex of finitely generated projective F_l[pi]-modules. To prove this result, we extend Wall's discussions of finiteness obstructions to l-profinite complete spaces with finite fundamental group.
title A necessary condition for liftings of positive characteristic varieties with finite fundamental groups
topic Algebraic Topology
Algebraic Geometry
url https://arxiv.org/abs/2506.07914