fact: Definition cong_ker (s : Sort σ) : Relation (A s) := λ (x y : A s), f s x = f s y.
imports: HSet Colimits.Quotient Modalities.ReflectiveSubuniverse Classes.interfaces.canonical_names Classes.theory.ua_isomorphic Classes.theory.ua_subalgebra Classes.theory.ua_quotient_algebra