Theorem rexeqtrrdv 3324

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 3320	. 2 ⊢ (𝜑 → (∃𝑥 ∈ 𝐵 𝜓 ↔ ∃𝑥 ∈ 𝐴 𝜓))
4	1, 3	mpbird 260	1 ⊢ (𝜑 → ∃𝑥 ∈ 𝐵 𝜓)

This proof depends on syntax axioms:   → wi 4   = wceq 1569  ∃wrex 3086

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1942  ax-6 1999  ax-7 2040  ax-9 2154  ax-ext 2732

This proof depends on definitions:  df-bi 210  df-an 402  df-ex 1812  df-cleq 2752  df-rex 3087

This theorem is used by:  zornn0g  10586  ablfacrplem  20286  ablfac2  20310  2ndcctbss  23779  1stcelcls  23785  wwlksnextsurj  30494  primrootsunit1  43240