7 papers
Potential isotriviality of isocrystals and proper covers
Adrian Langer, Lei Zhang
We study convergent and overconvergent isocrystals that become trivial after pullback along a proper surjective morphism. On a geometrically unibranch variety over an algebraically…
The Lange-Stuhler Theorem via Gerbes
Lei Zhang
We recast the Lange-Stuhler theorem as the universal property of a -cartesian square of classifying stacks. This formulation shows that every Frobenius-periodic vector bundle of…
Isocrystals on unibranch varieties and open immersions
Adrian Langer, Lei Zhang
We prove that for a connected, geometrically unibranch variety over a perfect field of positive characteristic and a dense open subset , the canonical homomorphism…
Integrability of Lawson-Osserman Cone and its Applications
Qi Ding, Lei Zhang
In this paper, we characterize all eigenfunctions corresponding to nonpositive eigenvalues of the Jacobi operator of the link of the Lawson-Osserman cone in $\math…
The pro-étale fundamental group of singular schemes
Jiu-Kang Yu, Lei Zhang
We compute the pro-étale fundamental group of a connected Nagata J-2 scheme in terms of the étale fundamental groups of the normalizations of its irreducible components and a discr…
-divided bundles on normal -finite schemes
Adrian Langer, Lei Zhang
In this paper we study -divided bundles on irreducible Noetherian normal -finite -schemes and we show that their Tannakian category is governed by the behaviour…
The étale fundamental group and -divided sheaves in characteristic
Xiaotao Sun, Lei Zhang
We investigate how the étale fundamental group controls local systems in characteristic , namely -divided sheaves. In analogy with Grothendieck-Malcev's results for discrete…