## Cohomological Invariants for G-Galois Algebras and Self-Dual Normal Bases

Cohomological Invariants for G-Galois Algebras and Self-Dual Normal Bases. We define degree two cohomological invariants for $G$-Galois algebras over fields of characteristic not 2, and use them to give necessary conditions for the existence of a self--dual normal basis. In some cases (for instance, when the field has cohomological dimension $\le 2$) we show that these conditions are also sufficient.

Published in:
Documenta Mathematica : Journal der deutschen Mathematiker-Vereinigung, 22, 1-24
Year:
2017
ISSN:
1431-0635
Laboratories: