Theorem rexeqf 1322

Description: Equality theorem for restricted existential quantifier, with bound variable hypotheses instead of distinct variable restrictions.

Hypotheses

Ref	Expression
raleqf.1	|- (y e. A -> A.x y e. A)
raleqf.2	|- (y e. B -> A.x y e. B)

Assertion

Ref	Expression
rexeqf	|- (A = B -> (E.x e. A ph <-> E.x e. B ph))

Distinct variable group(s):   y,A   y,B   x,y

Proof of Theorem rexeqf

Step	Hyp	Ref	Expression
1		raleqf.1	. . . 4 |- (y e. A -> A.x y e. A)
2		raleqf.2	. . . 4 |- (y e. B -> A.x y e. B)
3	1, 2	hbeq 1171	. . 3 |- (A = B -> A.x A = B)
4		eleq2 1150	. . . 4 |- (A = B -> (x e. A <-> x e. B))
5	4	anbi1d 469	. . 3 |- (A = B -> ((x e. A /\ ph) <-> (x e. B /\ ph)))
6	3, 5	biexd 783	. 2 |- (A = B -> (E.x(x e. A /\ ph) <-> E.x(x e. B /\ ph)))
7		df-rex 1206	. 2 |- (E.x e. A ph <-> E.x(x e. A /\ ph))
8		df-rex 1206	. 2 |- (E.x e. B ph <-> E.x(x e. B /\ ph))
9	6, 7, 8	3bitr4g 428	1 |- (A = B -> (E.x e. A ph <-> E.x e. B ph))

Syntax hints:   -> wi 2   <-> wb 127   /\ wa 196  A.wal 672  E.wex 678   = wceq 1091   e. wcel 1092  E.wrex 1202

This theorem is referenced by:  rexeq 1325  zfrep6 2744

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-6 675  ax-7 676  ax-gen 677  ax-9 799  ax-17 925  ax-ext 1074

This theorem depends on definitions:  df-bi 128  df-an 198  df-ex 679  df-cleq 1097  df-clel 1099  df-rex 1206

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