Cohomological invariants of hermitian forms that detect hyperbolicity

Fuente: arXiv
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Main Authors: Hu, Yong, Lourdeaux, Alexandre
Format: Preprint
Published: 2026
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author Hu, Yong
Lourdeaux, Alexandre
author_facet Hu, Yong
Lourdeaux, Alexandre
contents By using unramified cohomology groups, we construct a full sequence of cohomological invariants for hermitian forms of any type (orthogonal, symplectic or unitary) that can be used to detect hyperbolicity. The base central simple algebras can have arbitrary degree and the base field can have arbitrary characteristic. In the orthogonal case, we work with hermitian pairs, and we apply our construction to show that over fields of separable dimension 3, hermitian pairs over quaternion algebras with trivial classical invariants are hyperbolic. This last result extends a result of Berhuy to arbitrary characteristic.
format Preprint
id arxiv_https___arxiv_org_abs_2604_00581
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Cohomological invariants of hermitian forms that detect hyperbolicity
Hu, Yong
Lourdeaux, Alexandre
Rings and Algebras
11E39, 16W10, 11E57, 11E72
By using unramified cohomology groups, we construct a full sequence of cohomological invariants for hermitian forms of any type (orthogonal, symplectic or unitary) that can be used to detect hyperbolicity. The base central simple algebras can have arbitrary degree and the base field can have arbitrary characteristic. In the orthogonal case, we work with hermitian pairs, and we apply our construction to show that over fields of separable dimension 3, hermitian pairs over quaternion algebras with trivial classical invariants are hyperbolic. This last result extends a result of Berhuy to arbitrary characteristic.
title Cohomological invariants of hermitian forms that detect hyperbolicity
topic Rings and Algebras
11E39, 16W10, 11E57, 11E72
url https://arxiv.org/abs/2604.00581