Theorem rexeqOLD 3339

Description: Obsolete version of raleq 3321 as of 9-Mar-2025. (Contributed by NM, 29-Oct-1995.) Remove usage of ax-10 2139, ax-11 2155, and ax-12 2175. (Revised by Steven Nguyen, 30-Apr-2023.) (New usage is discouraged.) (Proof modification is discouraged.)

Assertion

Ref	Expression
rexeqOLD	⊢ (𝐴 = 𝐵 → (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑥 ∈ 𝐵 𝜑))

Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Allowed substitution hint:   𝜑(𝑥)

Proof of Theorem rexeqOLD

Step	Hyp	Ref	Expression
1		biidd 262	. 2 ⊢ (𝐴 = 𝐵 → (𝜑 ↔ 𝜑))
2	1	rexeqbi1dv 3337	1 ⊢ (𝐴 = 𝐵 → (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑥 ∈ 𝐵 𝜑))

Syntax hints:   → wi 4   ↔ wb 206   = wceq 1537  ∃wrex 3068

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1908  ax-6 1965  ax-7 2005  ax-9 2116  ax-ext 2706

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1777  df-cleq 2727  df-rex 3069

This theorem is referenced by: (None)