Theorem alnex ≪ | index | src | ≫

theorem alnex {x: nat} (a: wff x): $ A. x ~a <-> ~E. x a $;

Step	Hyp	Ref	Expression
1		notnot	A. x ~a <-> ~~A. x ~a
2	1	conv ex	A. x ~a <-> ~E. x a

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp)