mathlib

7af08859 - feat(category_theory/epi_mono): preserves/reflects properties for epi/split_epi (#15857)

feat(category_theory/epi_mono): preserves/reflects properties for epi/split_epi (#15857) This PR shows that split epi/mono are preserved by any functor, and reflected by fully faithful functors. Moreover, `iff` lemmas are obtained for functors which both preserve and reflect epimorphisms (resp. monomorphisms). Co-authored-by: Joël Riou <37772949+joelriou@users.noreply.github.com>