I just want to point out that the tag (abstract-algebra) is deprecated on MO, see
the tag-info. (I'll leave to the OP and to more experienced users the decision what tags should be used for this question.) Unrelated to this - the formulation "Theorem 1.1 and Theorem 1.3 of split extension" seems a bit unusual; did you perhaps wanted to have the name of the paper in the place where you wrote "split extension"? —
Martin Sleziak 1 min ago