A morphism f: A → B with a two-sided inverse. Captures 'the right notion of sameness' in every category: bijection in Set, homeomorphism in Top, isomorphism of groups in Grp.
A morphism f: A → B with a two-sided inverse. Captures 'the right notion of sameness' in every category: bijection in Set, homeomorphism in Top, isomorphism of groups in Grp.