Theorem mobiiOLD

Description: Obsolete version of mobii as of 24-Sep-2023. (Contributed by NM, 9-Mar-1995) (Revised by Mario Carneiro, 17-Oct-2016) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	mobii.1	|- ( ps <-> ch )
Assertion	mobiiOLD	|- ( E* x ps <-> E* x ch )

Proof

Step	Hyp	Ref	Expression
1		mobii.1	|- ( ps <-> ch )
2		mobi	|- ( A. x ( ps <-> ch ) -> ( E* x ps <-> E* x ch ) )
3	2 1	mpg	|- ( E* x ps <-> E* x ch )