Galois Groups of Symmetric Cubic Surfaces

Fuente: arXiv
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Main Authors: Pichon-Pharabod, Eric, Telen, Simon
Format: Preprint
Published: 2025
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author Pichon-Pharabod, Eric
Telen, Simon
author_facet Pichon-Pharabod, Eric
Telen, Simon
contents The Galois group of a family of cubic surfaces is the monodromy group of the 27 lines of its generic fibre. We describe a method to compute this group for linear systems of cubic surfaces using certified numerical computations. Applying this to all families which are invariant under the action of a subgroup of $S_5$, we find that the Galois group is often much smaller than the Weyl group $W(E_6)$. As a byproduct, we compute the discriminants of these~families. Our method allows to compute the monodromy representation on homology of any family of generically smooth projective hypersurfaces. To illustrate this broader scope, we include computations for symmetric quartic surfaces.
format Preprint
id arxiv_https___arxiv_org_abs_2509_06785
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Galois Groups of Symmetric Cubic Surfaces
Pichon-Pharabod, Eric
Telen, Simon
Algebraic Geometry
14D05, 65H14 (Primary) 14Q10, 32S40, 32G20, 55R80 (Secondary)
The Galois group of a family of cubic surfaces is the monodromy group of the 27 lines of its generic fibre. We describe a method to compute this group for linear systems of cubic surfaces using certified numerical computations. Applying this to all families which are invariant under the action of a subgroup of $S_5$, we find that the Galois group is often much smaller than the Weyl group $W(E_6)$. As a byproduct, we compute the discriminants of these~families. Our method allows to compute the monodromy representation on homology of any family of generically smooth projective hypersurfaces. To illustrate this broader scope, we include computations for symmetric quartic surfaces.
title Galois Groups of Symmetric Cubic Surfaces
topic Algebraic Geometry
14D05, 65H14 (Primary) 14Q10, 32S40, 32G20, 55R80 (Secondary)
url https://arxiv.org/abs/2509.06785