Gendo-Frobenius algebras and comultiplication

Abstract

Two large classes of algebras, Frobenius algebras and gendo-symmetric algebras, are characterised by thenexistence of a comultiplication with some special properties. Symmetric algebras are both Frobenius and gendo-symmetric. Kerner and Yamagata investigated two variations of gendo-symmetric algebras and in fact these two variations contain gendo-symmetric and Frobenius algebras. We call one of these variations gendo-Frobenius algebras. In this thesis, we construct a comultiplication for gendo-Frobenius algebras, which specialises to the known comultiplications on Frobenius algebras and on gendo-symmetric algebras. Moreover, we show that Frobenius algebras are precisely those gendo-Frobenius algebras that have a counit compatible with this comultiplication.