Theorem bj-nnfei

Description: Nonfreeness implies the equivalent of ax5e , inference form. (Contributed by BJ, 22-Sep-2024)

	Ref	Expression
Hypothesis	bj-nnfei.1	|- F// x ph
Assertion	bj-nnfei	|- ( E. x ph -> ph )

Proof

Step	Hyp	Ref	Expression
1		bj-nnfei.1	|- F// x ph
2		bj-nnfe	|- ( F// x ph -> ( E. x ph -> ph ) )
3	1 2	ax-mp	|- ( E. x ph -> ph )