Theorem rexeq 2704

Description: Equality theorem for restricted existential quantifier. (Contributed by NM, 29-Oct-1995.)

Assertion

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

Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Allowed substitution hint:   𝜑(𝑥)

Proof of Theorem rexeq

Step	Hyp	Ref	Expression
1		nfcv 2349	. 2 ⊢ Ⅎ𝑥𝐴
2		nfcv 2349	. 2 ⊢ Ⅎ𝑥𝐵
3	1, 2	rexeqf 2700	1 ⊢ (𝐴 = 𝐵 → (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑥 ∈ 𝐵 𝜑))

Syntax hints:   → wi 4   ↔ wb 105   = wceq 1373  ∃wrex 2486

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 711  ax-5 1471  ax-7 1472  ax-gen 1473  ax-ie1 1517  ax-ie2 1518  ax-8 1528  ax-10 1529  ax-11 1530  ax-i12 1531  ax-bndl 1533  ax-4 1534  ax-17 1550  ax-i9 1554  ax-ial 1558  ax-i5r 1559  ax-ext 2188

This theorem depends on definitions:  df-bi 117  df-tru 1376  df-nf 1485  df-sb 1787  df-cleq 2199  df-clel 2202  df-nfc 2338  df-rex 2491

This theorem is referenced by:  rexeqi  2708  rexeqdv  2710  rexeqbi1dv  2716  unieq  3864  bnd2  4224  exss  4278  qseq1  6682  finexdc  7013  supeq1  7102  isomni  7252  ismkv  7269  sup3exmid  9045  exmidunben  12867  neifval  14682  cnprcl2k  14748  bj-nn0sucALT  16048  strcoll2  16053  strcollnft  16054  strcollnfALT  16056  sscoll2  16058