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Theorem rexeqOLD 3330
Description: Obsolete version of raleq 3316 as of 9-Mar-2025. (Contributed by NM, 29-Oct-1995.) Remove usage of ax-10 2129, ax-11 2146, and ax-12 2163. (Revised by Steven Nguyen, 30-Apr-2023.) (New usage is discouraged.) (Proof modification is discouraged.)
Assertion
Ref Expression
rexeqOLD (𝐴 = 𝐵 → (∃𝑥𝐴 𝜑 ↔ ∃𝑥𝐵 𝜑))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵
Allowed substitution hint:   𝜑(𝑥)

Proof of Theorem rexeqOLD
StepHypRef Expression
1 biidd 262 . 2 (𝐴 = 𝐵 → (𝜑𝜑))
21rexeqbi1dv 3328 1 (𝐴 = 𝐵 → (∃𝑥𝐴 𝜑 ↔ ∃𝑥𝐵 𝜑))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 205   = wceq 1533  wrex 3064
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-9 2108  ax-ext 2697
This theorem depends on definitions:  df-bi 206  df-an 396  df-ex 1774  df-cleq 2718  df-rex 3065
This theorem is referenced by: (None)
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