fact: Definition ab_image_embedding {A B : AbGroup} (f : A $-> B) `{IsEmbedding f} : NormalSubgroup B := {| normalsubgroup_subgroup := grp_image_embedding f; normalsubgroup_isnormal := _ |}.
imports: Basics Types Classes.interfaces.canonical_names (Zero, zero) Classes.interfaces.abstract_algebra (IsAbGroup(..), abgroup_group, abgroup_commutative) Algebra.Groups.Group Algebra.Groups.Subgroup Algebra.Groups.QuotientGroup WildCat