Implication details
Claim: Given a morphism whose category is preadditive, if it is a regular epimorphism, then it is a normal epimorphism.
Proof: This follows from the dual implication.
This implication has a dual.
Claim: Given a morphism whose category is preadditive, if it is a regular epimorphism, then it is a normal epimorphism.
This implication has a dual.