Theorem cbvrex2vw 2779

Description: Change bound variables of double restricted universal quantification, using implicit substitution. Version of cbvrex2v 2781 with a disjoint variable condition, which does not require ax-13 2204. (Contributed by FL, 2-Jul-2012.) (Revised by GG, 10-Jan-2024.)

Hypotheses

Ref	Expression
cbvrex2vw.1	|- ( x = z -> ( ph <-> ch ) )
cbvrex2vw.2	|- ( y = w -> ( ch <-> ps ) )

Assertion

Ref	Expression
cbvrex2vw	|- ( E. x e. A E. y e. B ph <-> E. z e. A E. w e. B ps )

Distinct variable groups:   x, z   y, w   x, A, z   w, B   x, B, y, z   ch, w   ch, x   ph, z   ps, y

Allowed substitution hints:   ph( x, y, w)   ps( x, z, w)   ch( y, z)   A( y, w)

Proof of Theorem cbvrex2vw

Step	Hyp	Ref	Expression
1		cbvrex2vw.1	. . . 4 |- ( x = z -> ( ph <-> ch ) )
2	1	rexbidv 2533	. . 3 |- ( x = z -> ( E. y e. B ph <-> E. y e. B ch ) )
3	2	cbvrexvw 2772	. 2 |- ( E. x e. A E. y e. B ph <-> E. z e. A E. y e. B ch )
4		cbvrex2vw.2	. . . 4 |- ( y = w -> ( ch <-> ps ) )
5	4	cbvrexvw 2772	. . 3 |- ( E. y e. B ch <-> E. w e. B ps )
6	5	rexbii 2539	. 2 |- ( E. z e. A E. y e. B ch <-> E. z e. A E. w e. B ps )
7	3, 6	bitri 184	1 |- ( E. x e. A E. y e. B ph <-> E. z e. A E. w e. B ps )

Syntax hints:   -> wi 4   <-> wb 105   E.wrex 2511

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1495  ax-gen 1497  ax-ie1 1541  ax-ie2 1542  ax-8 1552  ax-4 1558  ax-17 1574  ax-i9 1578  ax-ial 1582

This theorem depends on definitions:  df-bi 117  df-tru 1400  df-nf 1509  df-clel 2227  df-rex 2516

This theorem is referenced by:  4sqlem2  12961  2sqlem9  15852