Biproduct

Summary

A biproduct of two objects is a single object that is at the same time their product and their coproduct, with compatible projections and inclusions. It generalizes the direct sum $A \oplus B$ of abelian groups or modules, which has both universal properties. Additive categories are the preadditive categories with a zero object in which all binary biproducts exist. In a preadditive category, a finite product is automatically a biproduct.