fact: Record AbSESMorphism {A X B Y : AbGroup@{u}} {E : AbSES B A} {F : AbSES Y X} := { component1 : A $-> X; component2 : middle E $-> middle F; component3 : B $-> Y; left_square : (inclusion _) $o component1 == component2 $o (inclusion _); right_square : (projection _) $o component2 == component3 $o (projection _); }.
imports: Basics Types Truncations.Core HSet WildCat Groups.QuotientGroup Groups.ShortExactSequence AbelianGroup AbGroups.Biproduct AbHom Homotopy.ExactSequence Pointed Modalities.ReflectiveSubuniverse