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Éloan Rapion

Publications and source records attributed to Éloan Rapion.

2 recordsLinked to original sources

Intermediate hyperbolicity of varieties supporting a variation of Hodge structure

Let $\bar{V}$ be a connected smooth complex projective variety. Let $D \subset \bar{V}$ be a normal crossing divisor. Let $\mathbb{V}$ be a complex polarizable variation of Hodge structure on $V := \bar{V} \setminus D$. Suppose that the period map of $\mathbb{V}$ is immersive at a point of $V$. We prove that for every integer $p$ with $1 \leq p \leq \dim V$, the vector bundle $Ω_{\bar{V}}^p(\log D)$ is L-big (i.e. the tautological line bundle on $\mathbb{P}Ω_{\bar{V}}^p(\log D)$ is big). If the local monodromy is quasi-unipotent, we give a method to determine an $m \in \mathbb{N}$ such that if $p > m$, then $Ω_{\bar{V}}^p(\log D)$ is moreover Viehweg-big. We give the optimal value of $m$ explicitly when $V$ is a locally symmetric variety. We prove that if $V$ is a finite étale cover of the fine moduli space of smooth quintic threefolds, the result holds for $m = 90$ (in this case $\dim V = 101$). The proof of the previous results is based on a study of an augmented base locus associated with $Ω_{\bar{V}}^p(\log D)$. In the case of locally symmetric varieties, we introduce ``higher degree characteristic subvarieties'', generalizing the characteristic subvariety defined by Mok in the case $p = 1$, and prove that they coincide with these augmented base loci.

math.AG↗

Isotriviality of families of curves parametrized by $\mathcal{A}_g(n)$

We prove that for every integers $g, h\geq 2, n \geq 3$, for all but finitely many prime numbers $p$, for every field $k$ of characteristic $0$ or $p$, every separable family of smooth projective curves of genus $h$ over $\mathcal{A}_g(n) \otimes k$ is isotrivial. To prove this, we compute the common vanishing locus of the absolutely logarithmic symmetric forms on a smooth complex algebraic variety whose universal covering is biholomorphic to an irreducible bounded symmetric domain of rank at least $2$.

math.AG↗