Theorem rexeqtrrdv 3314

Description: Substitution of equal classes into a restricted existential quantifier. (Contributed by Matthew House, 21-Jul-2025.)

Hypotheses

Ref	Expression
rexeqtrrdv.1	⊢ (𝜑 → ∃𝑥 ∈ 𝐴 𝜓)
rexeqtrrdv.2	⊢ (𝜑 → 𝐵 = 𝐴)

Assertion

Ref	Expression
rexeqtrrdv	⊢ (𝜑 → ∃𝑥 ∈ 𝐵 𝜓)

Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑥)

Proof of Theorem rexeqtrrdv

Step	Hyp	Ref	Expression
1		rexeqtrrdv.1	. 2 ⊢ (𝜑 → ∃𝑥 ∈ 𝐴 𝜓)
2		rexeqtrrdv.2	. . 3 ⊢ (𝜑 → 𝐵 = 𝐴)
3	2	rexeqdv 3310	. 2 ⊢ (𝜑 → (∃𝑥 ∈ 𝐵 𝜓 ↔ ∃𝑥 ∈ 𝐴 𝜓))
4	1, 3	mpbird 257	1 ⊢ (𝜑 → ∃𝑥 ∈ 𝐵 𝜓)

Syntax hints:   → wi 4   = wceq 1540  ∃wrex 3061

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2008  ax-9 2119  ax-ext 2708

This theorem depends on definitions:  df-bi 207  df-an 396  df-ex 1780  df-cleq 2728  df-rex 3062

This theorem is referenced by:  zornn0g  10524  ablfacrplem  20053  ablfac2  20077  2ndcctbss  23398  1stcelcls  23404  wwlksnextsurj  29887  primrootsunit1  42115