CatDat

Implication Details

Assumptions: initial objectright cancellative

Conclusions: strict initial object

Reason: Let f:A0f : A \to 0 be a morphism. Let g:0Ag : 0 \to A be the unique morphism. It is an epimorphism by assumption. Also, fg=id0f \circ g = \mathrm{id}_0 since 00 is initial. But then gg is a split monomorphism and an epimorphism, hence an isomorphism.