Cohomological invariants of classical Weyl groups modulo 2

TL;DR

This paper characterizes the cohomological invariants of classical Weyl groups modulo 2, revealing that they are fully determined by their restrictions to specific abelian subgroups generated by reflections.

Contribution

It provides a complete description of the cohomological invariants of classical Weyl groups modulo 2, extending previous results to a broader class of groups.

Findings

All cohomological invariants are determined by restrictions to abelian reflection subgroups.

Explicit descriptions of invariants for classical Weyl groups are provided.

The approach simplifies understanding invariants via subgroup restrictions.

Abstract

In a previous paper, we showed that all the cohomological invariants of Weyl groups are completely determined by their restrictions to the abelian subgroups generated by reflections. Using this principle, we describe all the cohomological invariants of the Weyl groups of classical type modulo 2.