(**** NEQ_symm  *****)
Definition NEQ (A B : Ens) := ~ EQ A B.
Section neq_symm_proof.
Variable A : Ens.
Variable B : Ens.
Hypothesis k : NEQ A B.
Hypothesis m : EQ B A.
Let step1 : EQ A B.
Proof EQ_symm B A m.

Lemma neq_symm_Out : False.
Proof k step1.