The map to the orbifold base need not be an orbifold map

Fuente: arXiv
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Autor principal: Bartsch, Finn
Formato: Preprint
Publicado: 2026
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author Bartsch, Finn
author_facet Bartsch, Finn
contents We give an explicit example of a fibration $f \colon X \to Y$ between smooth projective varieties whose "orbifold base" $Δ_f$ in the sense of Campana has the property that the induced morphism $X \to (Y, Δ_f)$ is not a morphism of C-pairs (i.e., it is not an "orbifold morphism"). We however also show that this cannot happen if $f$ is "neat" and $(Y, Δ_f)$ is sufficiently well-behaved. Finally, we discuss the implications of this statement towards conjectures of Campana aiming to give algebro-geometric characterizations of those varieties which either admit a dense entire curve or a potentially dense set of integral points.
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publishDate 2026
record_format arxiv
spellingShingle The map to the orbifold base need not be an orbifold map
Bartsch, Finn
Algebraic Geometry
14E22 (Primary) 14G05, 32Q45 (Secondary)
We give an explicit example of a fibration $f \colon X \to Y$ between smooth projective varieties whose "orbifold base" $Δ_f$ in the sense of Campana has the property that the induced morphism $X \to (Y, Δ_f)$ is not a morphism of C-pairs (i.e., it is not an "orbifold morphism"). We however also show that this cannot happen if $f$ is "neat" and $(Y, Δ_f)$ is sufficiently well-behaved. Finally, we discuss the implications of this statement towards conjectures of Campana aiming to give algebro-geometric characterizations of those varieties which either admit a dense entire curve or a potentially dense set of integral points.
title The map to the orbifold base need not be an orbifold map
topic Algebraic Geometry
14E22 (Primary) 14G05, 32Q45 (Secondary)
url https://arxiv.org/abs/2603.06083