General Theory
For an arbitrary field K, the Brauer group may be expressed in terms of Galois cohomology as follows:
Here, Ks is the separable closure of K, which coincides with the algebraic closure when K is a perfect field.
A generalisation of the Brauer group to the case of commutative rings by M. Auslander and O. Goldman, and more generally to schemes, was introduced by Alexander Grothendieck. In their approach, central simple algebras over a field are replaced with Azumaya algebras.
Read more about this topic: Brauer Group
Famous quotes containing the words general and/or theory:
“What is written without effort is in general read without pleasure.”
—Samuel Johnson (1709–1784)
“Lucretius
Sings his great theory of natural origins and of wise conduct; Plato
smiling carves dreams, bright cells
Of incorruptible wax to hive the Greek honey.”
—Robinson Jeffers (1887–1962)