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Main Authors: Luo, Ma, Watanabe, Tatsunari
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2601.01336
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author Luo, Ma
Watanabe, Tatsunari
author_facet Luo, Ma
Watanabe, Tatsunari
contents We study the relative pro-$\ell$ and continuous relative completions of the algebraic fundamental groups of universal curves over the moduli stack of curves with unordered marked points in positive characteristic. Using specialization and homotopy exact sequences, we compare the ordered and unordered settings and prove that the natural projection from the relative completion of the universal curve over the unordered moduli stack admits no section in positive characteristic. This yields a non-splitting result for the corresponding projection on algebraic fundamental groups. The present paper is a sequel to our earlier work in characteristic zero.
format Preprint
id arxiv_https___arxiv_org_abs_2601_01336
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the universal curve with unordered marked points in positive characteristic
Luo, Ma
Watanabe, Tatsunari
Algebraic Geometry
We study the relative pro-$\ell$ and continuous relative completions of the algebraic fundamental groups of universal curves over the moduli stack of curves with unordered marked points in positive characteristic. Using specialization and homotopy exact sequences, we compare the ordered and unordered settings and prove that the natural projection from the relative completion of the universal curve over the unordered moduli stack admits no section in positive characteristic. This yields a non-splitting result for the corresponding projection on algebraic fundamental groups. The present paper is a sequel to our earlier work in characteristic zero.
title On the universal curve with unordered marked points in positive characteristic
topic Algebraic Geometry
url https://arxiv.org/abs/2601.01336