Theorem ereldm 6646

Description: Equality of equivalence classes implies equivalence of domain membership. (Contributed by NM, 28-Jan-1996.) (Revised by Mario Carneiro, 12-Aug-2015.)

Hypotheses

Ref	Expression
ereldm.1	⊢ (𝜑 → 𝑅 Er 𝑋)
ereldm.2	⊢ (𝜑 → [𝐴]𝑅 = [𝐵]𝑅)

Assertion

Ref	Expression
ereldm	⊢ (𝜑 → (𝐴 ∈ 𝑋 ↔ 𝐵 ∈ 𝑋))

Proof of Theorem ereldm

Dummy variable 𝑥 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		ereldm.2	. . . . 5 ⊢ (𝜑 → [𝐴]𝑅 = [𝐵]𝑅)
2	1	eleq2d 2266	. . . 4 ⊢ (𝜑 → (𝑥 ∈ [𝐴]𝑅 ↔ 𝑥 ∈ [𝐵]𝑅))
3	2	exbidv 1839	. . 3 ⊢ (𝜑 → (∃𝑥 𝑥 ∈ [𝐴]𝑅 ↔ ∃𝑥 𝑥 ∈ [𝐵]𝑅))
4		ecdmn0m 6645	. . 3 ⊢ (𝐴 ∈ dom 𝑅 ↔ ∃𝑥 𝑥 ∈ [𝐴]𝑅)
5		ecdmn0m 6645	. . 3 ⊢ (𝐵 ∈ dom 𝑅 ↔ ∃𝑥 𝑥 ∈ [𝐵]𝑅)
6	3, 4, 5	3bitr4g 223	. 2 ⊢ (𝜑 → (𝐴 ∈ dom 𝑅 ↔ 𝐵 ∈ dom 𝑅))
7		ereldm.1	. . . 4 ⊢ (𝜑 → 𝑅 Er 𝑋)
8		erdm 6611	. . . 4 ⊢ (𝑅 Er 𝑋 → dom 𝑅 = 𝑋)
9	7, 8	syl 14	. . 3 ⊢ (𝜑 → dom 𝑅 = 𝑋)
10	9	eleq2d 2266	. 2 ⊢ (𝜑 → (𝐴 ∈ dom 𝑅 ↔ 𝐴 ∈ 𝑋))
11	9	eleq2d 2266	. 2 ⊢ (𝜑 → (𝐵 ∈ dom 𝑅 ↔ 𝐵 ∈ 𝑋))
12	6, 10, 11	3bitr3d 218	1 ⊢ (𝜑 → (𝐴 ∈ 𝑋 ↔ 𝐵 ∈ 𝑋))

Syntax hints:   → wi 4   ↔ wb 105   = wceq 1364  ∃wex 1506   ∈ wcel 2167  dom cdm 4664   Er wer 6598  [cec 6599

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 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-14 2170  ax-ext 2178  ax-sep 4152  ax-pow 4208  ax-pr 4243

This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-nf 1475  df-sb 1777  df-eu 2048  df-mo 2049  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-ral 2480  df-rex 2481  df-v 2765  df-sbc 2990  df-un 3161  df-in 3163  df-ss 3170  df-pw 3608  df-sn 3629  df-pr 3630  df-op 3632  df-br 4035  df-opab 4096  df-xp 4670  df-cnv 4672  df-dm 4674  df-rn 4675  df-res 4676  df-ima 4677  df-er 6601  df-ec 6603

This theorem is referenced by:  erth  6647  brecop  6693