Theorem erex 8748

Description: An equivalence relation is a set if its domain is a set. (Contributed by Rodolfo Medina, 15-Oct-2010.) (Proof shortened by Mario Carneiro, 12-Aug-2015.)

Assertion

Ref	Expression
erex	⊢ (𝑅 Er 𝐴 → (𝐴 ∈ 𝑉 → 𝑅 ∈ V))

Proof of Theorem erex

Step	Hyp	Ref	Expression
1		erssxp 8747	. . 3 ⊢ (𝑅 Er 𝐴 → 𝑅 ⊆ (𝐴 × 𝐴))
2		sqxpexg 7754	. . 3 ⊢ (𝐴 ∈ 𝑉 → (𝐴 × 𝐴) ∈ V)
3		ssexg 5298	. . 3 ⊢ ((𝑅 ⊆ (𝐴 × 𝐴) ∧ (𝐴 × 𝐴) ∈ V) → 𝑅 ∈ V)
4	1, 2, 3	syl2an 596	. 2 ⊢ ((𝑅 Er 𝐴 ∧ 𝐴 ∈ 𝑉) → 𝑅 ∈ V)
5	4	ex 412	1 ⊢ (𝑅 Er 𝐴 → (𝐴 ∈ 𝑉 → 𝑅 ∈ V))

Syntax hints:   → wi 4   ∈ wcel 2109  Vcvv 3464   ⊆ wss 3931   × cxp 5657   Er wer 8721

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-8 2111  ax-9 2119  ax-ext 2708  ax-sep 5271  ax-nul 5281  ax-pow 5340  ax-pr 5407  ax-un 7734

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1543  df-fal 1553  df-ex 1780  df-sb 2066  df-clab 2715  df-cleq 2728  df-clel 2810  df-ral 3053  df-rex 3062  df-rab 3421  df-v 3466  df-dif 3934  df-un 3936  df-in 3938  df-ss 3948  df-nul 4314  df-if 4506  df-pw 4582  df-sn 4607  df-pr 4609  df-op 4613  df-uni 4889  df-br 5125  df-opab 5187  df-xp 5665  df-rel 5666  df-cnv 5667  df-dm 5669  df-rn 5670  df-er 8724

This theorem is referenced by:  erexb  8749  qliftlem  8817  qshash  15848  qusaddvallem  17570  qusaddflem  17571  qusaddval  17572  qusaddf  17573  qusmulval  17574  qusmulf  17575  qusgrp2  19046  efgrelexlemb  19736  efgcpbllemb  19741  frgpuplem  19758  qusrng  20145  qusring2  20299  vitalilem2  25567  vitalilem3  25568  tgjustr  28458