Diads and their application to topoi
As a common generalisation of monads and comonads the author introduces the concept of a diad. He demonstrates that many of the constructions performable for monads resp. comonads can be extended to diads. In particular, for diads so called dialgebras can be constructed as common generalisation of algebras of a monad resp. coalgebras of a comonad. Main result: the category of dialgebras for a finite--limit preserving left diad on a topos is again a topos.
scientific article; zbMATH DE number 5659531