Theorem bj-ideqg1ALT 35263

Description: Alternate proof of bj-ideqg1 using brabga 5440 instead of the "unbounded" version bj-brab2a1 35247 or brab2a 5670. (Contributed by BJ, 25-Dec-2023.) (Proof modification is discouraged.) (New usage is discouraged.)

TODO: delete once bj-ideqg 35255 is in the main section.

Assertion

Ref	Expression
bj-ideqg1ALT	⊢ ((𝐴 ∈ 𝑉 ∨ 𝐵 ∈ 𝑊) → (𝐴 I 𝐵 ↔ 𝐴 = 𝐵))

Proof of Theorem bj-ideqg1ALT

Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		reli 5725	. . . 4 ⊢ Rel I
2	1	brrelex12i 5633	. . 3 ⊢ (𝐴 I 𝐵 → (𝐴 ∈ V ∧ 𝐵 ∈ V))
3	2	adantl 481	. 2 ⊢ (((𝐴 ∈ 𝑉 ∨ 𝐵 ∈ 𝑊) ∧ 𝐴 I 𝐵) → (𝐴 ∈ V ∧ 𝐵 ∈ V))
4		elex 3440	. . . . 5 ⊢ (𝐴 ∈ 𝑉 → 𝐴 ∈ V)
5	4	adantr 480	. . . 4 ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐴 = 𝐵) → 𝐴 ∈ V)
6		eleq1 2826	. . . . . 6 ⊢ (𝐴 = 𝐵 → (𝐴 ∈ 𝑊 ↔ 𝐵 ∈ 𝑊))
7	6	biimparc 479	. . . . 5 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 = 𝐵) → 𝐴 ∈ 𝑊)
8	7	elexd 3442	. . . 4 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 = 𝐵) → 𝐴 ∈ V)
9	5, 8	jaoian 953	. . 3 ⊢ (((𝐴 ∈ 𝑉 ∨ 𝐵 ∈ 𝑊) ∧ 𝐴 = 𝐵) → 𝐴 ∈ V)
10		eleq1 2826	. . . . . 6 ⊢ (𝐴 = 𝐵 → (𝐴 ∈ 𝑉 ↔ 𝐵 ∈ 𝑉))
11	10	biimpac 478	. . . . 5 ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐴 = 𝐵) → 𝐵 ∈ 𝑉)
12	11	elexd 3442	. . . 4 ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐴 = 𝐵) → 𝐵 ∈ V)
13		elex 3440	. . . . 5 ⊢ (𝐵 ∈ 𝑊 → 𝐵 ∈ V)
14	13	adantr 480	. . . 4 ⊢ ((𝐵 ∈ 𝑊 ∧ 𝐴 = 𝐵) → 𝐵 ∈ V)
15	12, 14	jaoian 953	. . 3 ⊢ (((𝐴 ∈ 𝑉 ∨ 𝐵 ∈ 𝑊) ∧ 𝐴 = 𝐵) → 𝐵 ∈ V)
16	9, 15	jca 511	. 2 ⊢ (((𝐴 ∈ 𝑉 ∨ 𝐵 ∈ 𝑊) ∧ 𝐴 = 𝐵) → (𝐴 ∈ V ∧ 𝐵 ∈ V))
17		eqeq12 2755	. . 3 ⊢ ((𝑥 = 𝐴 ∧ 𝑦 = 𝐵) → (𝑥 = 𝑦 ↔ 𝐴 = 𝐵))
18		df-id 5480	. . 3 ⊢ I = {⟨𝑥, 𝑦⟩ ∣ 𝑥 = 𝑦}
19	17, 18	brabga 5440	. 2 ⊢ ((𝐴 ∈ V ∧ 𝐵 ∈ V) → (𝐴 I 𝐵 ↔ 𝐴 = 𝐵))
20	3, 16, 19	pm5.21nd 798	1 ⊢ ((𝐴 ∈ 𝑉 ∨ 𝐵 ∈ 𝑊) → (𝐴 I 𝐵 ↔ 𝐴 = 𝐵))

Syntax hints:   → wi 4   ↔ wb 205   ∧ wa 395   ∨ wo 843   = wceq 1539   ∈ wcel 2108  Vcvv 3422   class class class wbr 5070   I cid 5479

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2110  ax-9 2118  ax-ext 2709  ax-sep 5218  ax-nul 5225  ax-pr 5347

This theorem depends on definitions:  df-bi 206  df-an 396  df-or 844  df-3an 1087  df-tru 1542  df-fal 1552  df-ex 1784  df-sb 2069  df-clab 2716  df-cleq 2730  df-clel 2817  df-ral 3068  df-rex 3069  df-rab 3072  df-v 3424  df-dif 3886  df-un 3888  df-in 3890  df-ss 3900  df-nul 4254  df-if 4457  df-sn 4559  df-pr 4561  df-op 4565  df-br 5071  df-opab 5133  df-id 5480  df-xp 5586  df-rel 5587

This theorem is referenced by: (None)