Section ieieep2.
Variable X : Ens.
Hypothesis i : IN X EmptySet.
Let step2_1 : False.
Proof EmptySet_th1 X i.
Proof false_implies_everything (IN X A) step2_1.
End ieieep2.
Let step2 : SUB EmptySet A.
Proof ieieep2_Out.

Lemma ieieep_Out : EQ A EmptySet.