Stefan Reppen

activity

20222024

collaborators

4 papers

math.AG2024

An Ogus Principle for Zip period maps: The Hasse invariant's vanishing order via `Frobenius and the Hodge filtration'

Wushi Goldring, Stefan Reppen

This paper generalizes a result of Ogus that, under certain technical conditions, the vanishing order of the Hasse invariant of a family $Y / X$ of $n$ -dimensional Calabi-Yau varieti…

math.AG2023

Moduli of $G$ -bundles under nonconnected group schemes and nondensity of essentially finite bundles

Ludvig Olsson, Stefan Reppen, Tuomas Tajakka

We prove the existence of a projective good moduli space of principal $G$ -bundles under nonconnected reductive group schemes $G$ over a smooth projective curve…

math.AG2023

On the Hasse invariant of Hilbert modular varieties mod $p$

Stefan Reppen

Let $F$ be a totally real field and let $S$ denote the geometric special fiber of a Hilbert modular variety associated to $F$ , at a prime unramified in $F$ . We show that the order…

math.AG2022

Essentially finite $G$ -torsors

Archia Ghiasabadi, Stefan Reppen

Let $X$ be a smooth projective curve of genus $g$ , defined over an algebraically closed field $k$ , and let $G$ be a connected reductive group over $k$ . We say that a $G$ -torsor is…

An Ogus Principle for Zip period maps: The Hasse invariant's vanishing order via `Frobenius and the Hodge filtration'

Moduli of G-bundles under nonconnected group schemes and nondensity of essentially finite bundles

On the Hasse invariant of Hilbert modular varieties mod p

Essentially finite G-torsors

Moduli of $G$ -bundles under nonconnected group schemes and nondensity of essentially finite bundles

On the Hasse invariant of Hilbert modular varieties mod $p$

Essentially finite $G$ -torsors