Coproducts internal to profinite spaces

We give a categorical explanation for many properties of profinite coproducts of profinite groups, which were previously proven on a case-by-case basis. All of these properties take the form "certain functors preserve profinite coproducts". We give various examples to show how our framework can be applied. We also point out connections to internal category theory and profinite Bass-Serre theory.

Publication Details

Journal
Advances in Mathematics
Published
2026-08-21
DOI
https://doi.org/10.1016/j.aim.2026.111209
Primary Topic
Homotopy and Cohomology in Algebraic Topology
Type
article
Field-Weighted Citation Impact
0.00

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article

Coproducts internal to profinite spaces

Advances in Mathematics
Homotopy and Cohomology in Algebraic Topology
article

Coproducts internal to profinite spaces

article en

Abstract

We give a categorical explanation for many properties of profinite coproducts of profinite groups, which were previously proven on a case-by-case basis. All of these properties take the form "certain functors preserve profinite coproducts". We give various examples to show how our framework can be applied. We also point out connections to internal category theory and profinite Bass-Serre theory.

Advances in MathematicsVol. 503
Engineering and Physical Sciences Research Council
Reduced inequalities
Openalex Percentile: Top 86%
Homotopy and Cohomology in Algebraic Topology
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