fact: Definition isexact_ext_contra_sixterm_ii `{Funext} {B A G : AbGroup} (E : AbSES B A) : IsExact (Tr (-1)) (fmap10 (A:=Group^op) ab_hom (projection E) G) (fmap10 (A:=Group^op) ab_hom (inclusion E) G).
imports: Basics Types WildCat HSet Pointed.Core Pointed.pTrunc Pointed.pEquiv Modalities.ReflectiveSubuniverse Truncations.Core Truncations.SeparatedTrunc AbGroups Homotopy.ExactSequence AbSES.Core AbSES.Pullback AbSES.Pushout BaerSum Ext PullbackFiberSequence