Theorem ex_elim_abs ≪ | index | src | ≫

\ex消除(不出现)

theorem ex_elim_abs (A: wff) {x: set}: $ \ex x A \imp A $;

Step	Hyp	Ref	Expression
1		neg_imp_swap	(\neg A \imp \fo x \neg A) \imp \neg \fo x \neg A \imp A
2	1	conv ex	(\neg A \imp \fo x \neg A) \imp \ex x A \imp A
3		fo_intro_abs	\neg A \imp \fo x \neg A
4	2, 3	ax_mp	\ex x A \imp A

Axiom use

Logic (ax_mp, ax_1, ax_2, ax_3, ax_5)