diff --git a/library/hott/algebra/precategory/morphism.lean b/library/hott/algebra/precategory/morphism.lean index b9a83bb09..6bda4626e 100644 --- a/library/hott/algebra/precategory/morphism.lean +++ b/library/hott/algebra/precategory/morphism.lean @@ -46,10 +46,6 @@ namespace morphism theorem id_is_iso [instance] : is_iso (ID a) := is_iso.mk !id_compose !id_compose - -- In a precategory, equal objects are isomorphic - definition iso_of_path (p : a ≈ b) : Σ (f : hom a b), is_iso f := - path.rec_on p ⟨ id , id_is_iso ⟩ - theorem inverse_is_iso [instance] (f : a ⟶ b) [H : is_iso f] : is_iso (f⁻¹) := is_iso.mk !compose_inverse !inverse_compose @@ -150,6 +146,10 @@ namespace morphism --is_equivalence.mk (is_reflexive.mk refl) (is_symmetric.mk symm) (is_transitive.mk trans) end isomorphic + -- In a precategory, equal objects are isomorphic + definition iso_of_path (p : a ≈ b) : isomorphic a b := + path.rec_on p (isomorphic.mk id) + inductive is_mono [class] (f : a ⟶ b) : Type := mk : (∀c (g h : hom c a), f ∘ g ≈ f ∘ h → g ≈ h) → is_mono f inductive is_epi [class] (f : a ⟶ b) : Type :=