End ieieep1.
Let step1 : SUB A EmptySet.
Proof ieieep1_Out.
Section ieieep2.
Variable X : Ens.
Hypothesis i : IN X EmptySet.
Let step2_1 : False.
Proof EmptySet_th1 X i.

Lemma ieieep2_Out : IN X A.
Proof false_implies_everything (IN X A) step2_1.