Classification of division gradings on finite-dimensional simple real algebras

Abstract

We classify, up to isomorphism and up to equivalence, division gradings (by abelian groups) on finite-dimensional simple real algebras. Gradings on finite-dimensional simple algebras are determined by division gradings, so our results give the classification, up to isomorphism, of (not necessarily division) gradings on such algebras. Linear algebra over the field of two elements plays an interesting role in the proofs.