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Theorem cbvralsvwOLDOLD 3321
Description: Obsolete version of cbvralsvw 3318 as of 8-Mar-2025. (Contributed by NM, 20-Nov-2005.) Avoid ax-13 2374. (Revised by GG, 10-Jan-2024.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
cbvralsvwOLDOLD (∀𝑥𝐴 𝜑 ↔ ∀𝑦𝐴 [𝑦 / 𝑥]𝜑)
Distinct variable groups:   𝑥,𝐴,𝑦   𝜑,𝑦   𝑥,𝑦
Allowed substitution hint:   𝜑(𝑥)

Proof of Theorem cbvralsvwOLDOLD
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 nfv 1913 . . 3 𝑧𝜑
2 nfs1v 2152 . . 3 𝑥[𝑧 / 𝑥]𝜑
3 sbequ12 2247 . . 3 (𝑥 = 𝑧 → (𝜑 ↔ [𝑧 / 𝑥]𝜑))
41, 2, 3cbvralw 3307 . 2 (∀𝑥𝐴 𝜑 ↔ ∀𝑧𝐴 [𝑧 / 𝑥]𝜑)
5 nfv 1913 . . 3 𝑦[𝑧 / 𝑥]𝜑
6 nfv 1913 . . 3 𝑧[𝑦 / 𝑥]𝜑
7 sbequ 2083 . . 3 (𝑧 = 𝑦 → ([𝑧 / 𝑥]𝜑 ↔ [𝑦 / 𝑥]𝜑))
85, 6, 7cbvralw 3307 . 2 (∀𝑧𝐴 [𝑧 / 𝑥]𝜑 ↔ ∀𝑦𝐴 [𝑦 / 𝑥]𝜑)
94, 8bitri 275 1 (∀𝑥𝐴 𝜑 ↔ ∀𝑦𝐴 [𝑦 / 𝑥]𝜑)
Colors of variables: wff setvar class
Syntax hints:  wb 206  [wsb 2064  wral 3063
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-8 2105  ax-10 2136  ax-11 2153  ax-12 2173
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 847  df-ex 1778  df-nf 1782  df-sb 2065  df-clel 2813  df-nfc 2890  df-ral 3064
This theorem is referenced by: (None)
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