Theorem erref 8766

Description: An equivalence relation is reflexive on its field. Compare Theorem 3M of [Enderton] p. 56. (Contributed by Mario Carneiro, 6-May-2013.) (Revised by Mario Carneiro, 12-Aug-2015.)

Hypotheses

Ref	Expression
ersymb.1	⊢ (𝜑 → 𝑅 Er 𝑋)
erref.2	⊢ (𝜑 → 𝐴 ∈ 𝑋)

Assertion

Ref	Expression
erref	⊢ (𝜑 → 𝐴𝑅𝐴)

Proof of Theorem erref

Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		erref.2	. . . 4 ⊢ (𝜑 → 𝐴 ∈ 𝑋)
2		ersymb.1	. . . . 5 ⊢ (𝜑 → 𝑅 Er 𝑋)
3		erdm 8756	. . . . 5 ⊢ (𝑅 Er 𝑋 → dom 𝑅 = 𝑋)
4	2, 3	syl 17	. . . 4 ⊢ (𝜑 → dom 𝑅 = 𝑋)
5	1, 4	eleqtrrd 2843	. . 3 ⊢ (𝜑 → 𝐴 ∈ dom 𝑅)
6		eldmg 5908	. . . 4 ⊢ (𝐴 ∈ 𝑋 → (𝐴 ∈ dom 𝑅 ↔ ∃𝑥 𝐴𝑅𝑥))
7	1, 6	syl 17	. . 3 ⊢ (𝜑 → (𝐴 ∈ dom 𝑅 ↔ ∃𝑥 𝐴𝑅𝑥))
8	5, 7	mpbid 232	. 2 ⊢ (𝜑 → ∃𝑥 𝐴𝑅𝑥)
9	2	adantr 480	. . 3 ⊢ ((𝜑 ∧ 𝐴𝑅𝑥) → 𝑅 Er 𝑋)
10		simpr 484	. . 3 ⊢ ((𝜑 ∧ 𝐴𝑅𝑥) → 𝐴𝑅𝑥)
11	9, 10, 10	ertr4d 8765	. 2 ⊢ ((𝜑 ∧ 𝐴𝑅𝑥) → 𝐴𝑅𝐴)
12	8, 11	exlimddv 1934	1 ⊢ (𝜑 → 𝐴𝑅𝐴)

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   = wceq 1539  ∃wex 1778   ∈ wcel 2107   class class class wbr 5142  dom cdm 5684   Er wer 8743

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1794  ax-4 1808  ax-5 1909  ax-6 1966  ax-7 2006  ax-8 2109  ax-9 2117  ax-ext 2707  ax-sep 5295  ax-nul 5305  ax-pr 5431

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1542  df-fal 1552  df-ex 1779  df-sb 2064  df-clab 2714  df-cleq 2728  df-clel 2815  df-ral 3061  df-rex 3070  df-rab 3436  df-v 3481  df-dif 3953  df-un 3955  df-ss 3967  df-nul 4333  df-if 4525  df-sn 4626  df-pr 4628  df-op 4632  df-br 5143  df-opab 5205  df-xp 5690  df-rel 5691  df-cnv 5692  df-co 5693  df-dm 5694  df-er 8746

This theorem is referenced by:  iserd  8772  ecref  8791  erth  8797  iiner  8830  erinxp  8832  nqerid  10974  enqeq  10975  qusgrp  19205  sylow2alem1  19636  sylow2alem2  19637  sylow2a  19638  efginvrel2  19746  efgsrel  19753  efgcpbllemb  19774  frgp0  19779  frgpnabllem1  19892  frgpnabllem2  19893  pcophtb  25063  pi1xfrf  25087  pi1xfr  25089  pi1xfrcnvlem  25090  prtlem10  38867  prjspner01  42640  prjspner1  42641