Holomorphic differentials of alternating four covers
Abstract
Suppose is an algebraically closed field of characteristic two, let be an alternating group on four letters, and let be the unique Sylow two-subgroup of . Let be a smooth projective irreducible curve over with a faithful -action such that the quotient curve is a projective line and the -cover is totally ramified, in the sense that it is ramified and every branch point is totally ramified. Under these assumptions, we determine the precise -module structure of the space of holomorphic differentials of over . We show that there are infinitely many different isomorphism classes of indecomposable -modules that can occur as direct summands, and we give precise formulas for the multiplicities with which they occur.
Cite
@article{arxiv.2510.15743,
title = {Holomorphic differentials of alternating four covers},
author = {Frauke M. Bleher and Margarita Bustos Gonzalez},
journal= {arXiv preprint arXiv:2510.15743},
year = {2025}
}
Comments
38 pages; appendix on indecomposable modules in characteristic 2