Theorem erex 8720

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 8719	. . 3 ⊢ (𝑅 Er 𝐴 → 𝑅 ⊆ (𝐴 × 𝐴))
2		sqxpexg 7755	. . 3 ⊢ (𝐴 ∈ 𝑉 → (𝐴 × 𝐴) ∈ V)
3		ssexg 5291	. . 3 ⊢ ((𝑅 ⊆ (𝐴 × 𝐴) ∧ (𝐴 × 𝐴) ∈ V) → 𝑅 ∈ V)
4	1, 2, 3	syl2an 607	. 2 ⊢ ((𝑅 Er 𝐴 ∧ 𝐴 ∈ 𝑉) → 𝑅 ∈ V)
5	4	ex 417	1 ⊢ (𝑅 Er 𝐴 → (𝐴 ∈ 𝑉 → 𝑅 ∈ V))

Syntax hints:   → wi 4   ∈ wcel 2143  Vcvv 3455   ⊆ wss 3906   × cxp 5661   Er wer 8692

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1825  ax-4 1839  ax-5 1940  ax-6 1997  ax-7 2038  ax-8 2145  ax-9 2153  ax-ext 2735  ax-sep 5258  ax-pow 5338  ax-pr 5406  ax-un 7734

This theorem depends on definitions:  df-bi 210  df-an 401  df-or 861  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1810  df-sb 2097  df-clab 2742  df-cleq 2755  df-clel 2838  df-ral 3080  df-rex 3090  df-rab 3417  df-v 3457  df-dif 3909  df-un 3911  df-in 3913  df-ss 3923  df-nul 4288  df-if 4489  df-pw 4565  df-sn 4591  df-pr 4593  df-op 4597  df-uni 4874  df-br 5111  df-opab 5175  df-xp 5669  df-rel 5670  df-cnv 5671  df-dm 5673  df-rn 5674  df-er 8695

This theorem is referenced by:  erexb  8721  qliftlem  8797  qshash  15881  qusaddvallem  17606  qusaddflem  17607  qusaddval  17608  qusaddf  17609  qusmulval  17610  qusmulf  17611  qusgrp2  19125  efgrelexlemb  19821  efgcpbllemb  19826  frgpuplem  19843  qusrng  20259  qusring2  20417  vitalilem2  25749  vitalilem3  25750  tgjustr  28724