3 papers
math.RA2025
Witt invariants of quaternionic forms
Nicolas Garrel
We describe all Witt invariants of anti-hermitian forms over a quaternion algebra with its canonical involution, and in particular all Witt invariants of orthogonal groups …
math.RA2023
An Artin-Schreier-type theory for signatures of hermitian forms over involutions
Nicolas Garrel
In the case of quadratic forms over a field, it is well-known that the prime spectrum of the Witt ring and the space of orderings of the field determine one another, through associ…
math.RA2023
Invariants cohomologiques de groupes algébriques et d'algèbres à involution
Nicolas Garrel
In order to study certain algebraic objects, and notably algebraic groups, Serre introduced the notion on invariants, in particular cohomological invariants. The construction of no…