(f : ∀ s, A s → B s) `{IsIsomorphism σ A B f} : A = B. Proof. apply (path_algebra _ _ (path_equiv_family (equiv_isomorphism f))). abstract ( funext u; exact (transport_forall_constant _ _ u @ path_operations_isomorphism f u)). Defined.
Require Import Import algebra_notations ne_list.notations.