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Theorem cbvrexf 2500
 Description: Rule used to change bound variables, using implicit substitution. (Contributed by FL, 27-Apr-2008.) (Revised by Mario Carneiro, 9-Oct-2016.) (Proof rewritten by Jim Kingdon, 10-Jun-2018.)
Hypotheses
Ref Expression
cbvralf.1 xA
cbvralf.2 yA
cbvralf.3 yφ
cbvralf.4 xψ
cbvralf.5 (x = y → (φψ))
Assertion
Ref Expression
cbvrexf (x A φy A ψ)

Proof of Theorem cbvrexf
Dummy variable z is distinct from all other variables.
StepHypRef Expression
1 nfv 1397 . . . 4 z(x A φ)
2 cbvralf.1 . . . . . 6 xA
32nfcri 2148 . . . . 5 x z A
4 nfs1v 1791 . . . . 5 x[z / x]φ
53, 4nfan 1433 . . . 4 x(z A [z / x]φ)
6 eleq1 2076 . . . . 5 (x = z → (x Az A))
7 sbequ12 1630 . . . . 5 (x = z → (φ ↔ [z / x]φ))
86, 7anbi12d 442 . . . 4 (x = z → ((x A φ) ↔ (z A [z / x]φ)))
91, 5, 8cbvex 1615 . . 3 (x(x A φ) ↔ z(z A [z / x]φ))
10 cbvralf.2 . . . . . 6 yA
1110nfcri 2148 . . . . 5 y z A
12 cbvralf.3 . . . . . 6 yφ
1312nfsb 1798 . . . . 5 y[z / x]φ
1411, 13nfan 1433 . . . 4 y(z A [z / x]φ)
15 nfv 1397 . . . 4 z(y A ψ)
16 eleq1 2076 . . . . 5 (z = y → (z Ay A))
17 sbequ 1697 . . . . . 6 (z = y → ([z / x]φ ↔ [y / x]φ))
18 cbvralf.4 . . . . . . 7 xψ
19 cbvralf.5 . . . . . . 7 (x = y → (φψ))
2018, 19sbie 1650 . . . . . 6 ([y / x]φψ)
2117, 20syl6bb 185 . . . . 5 (z = y → ([z / x]φψ))
2216, 21anbi12d 442 . . . 4 (z = y → ((z A [z / x]φ) ↔ (y A ψ)))
2314, 15, 22cbvex 1615 . . 3 (z(z A [z / x]φ) ↔ y(y A ψ))
249, 23bitri 173 . 2 (x(x A φ) ↔ y(y A ψ))
25 df-rex 2284 . 2 (x A φx(x A φ))
26 df-rex 2284 . 2 (y A ψy(y A ψ))
2724, 25, 263bitr4i 201 1 (x A φy A ψ)
 Colors of variables: wff set class Syntax hints:   → wi 4   ∧ wa 97   ↔ wb 98  Ⅎwnf 1325  ∃wex 1357   ∈ wcel 1369  [wsb 1621  Ⅎwnfc 2141  ∃wrex 2279 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 614  ax-5 1312  ax-7 1313  ax-gen 1314  ax-ie1 1358  ax-ie2 1359  ax-8 1371  ax-10 1372  ax-11 1373  ax-i12 1374  ax-bnd 1375  ax-4 1376  ax-17 1395  ax-i9 1399  ax-ial 1403  ax-i5r 1404  ax-ext 1998 This theorem depends on definitions:  df-bi 110  df-nf 1326  df-sb 1622  df-cleq 2009  df-clel 2012  df-nfc 2143  df-rex 2284 This theorem is referenced by:  cbvrex  2502
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