Theorem brlexod 35931

Description: Condition for two ordered pairs to be related by LexOrd. (Contributed by BTernaryTau, 20-Sep-2026.)

Hypotheses

Ref	Expression
brlexod.1	⊢ (𝜑 → 𝐴 ∈ On)
brlexod.2	⊢ (𝜑 → 𝐵 ∈ On)
brlexod.3	⊢ (𝜑 → 𝐶 ∈ On)
brlexod.4	⊢ (𝜑 → 𝐷 ∈ On)

Assertion

Ref	Expression
brlexod	⊢ (𝜑 → (⟨𝐴, 𝐵⟩LexOrd⟨𝐶, 𝐷⟩ ↔ (𝐴 ∈ 𝐶 ∨ (𝐴 = 𝐶 ∧ 𝐵 ∈ 𝐷))))

Proof of Theorem brlexod

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

Step	Hyp	Ref	Expression
1		brlexod.1	. . . 4 ⊢ (𝜑 → 𝐴 ∈ On)
2		brlexod.2	. . . 4 ⊢ (𝜑 → 𝐵 ∈ On)
3	1, 2	opelxpd 5689	. . 3 ⊢ (𝜑 → ⟨𝐴, 𝐵⟩ ∈ (On × On))
4		brlexod.3	. . . 4 ⊢ (𝜑 → 𝐶 ∈ On)
5		brlexod.4	. . . 4 ⊢ (𝜑 → 𝐷 ∈ On)
6	4, 5	opelxpd 5689	. . 3 ⊢ (𝜑 → ⟨𝐶, 𝐷⟩ ∈ (On × On))
7	3, 6	jca 521	. 2 ⊢ (𝜑 → (⟨𝐴, 𝐵⟩ ∈ (On × On) ∧ ⟨𝐶, 𝐷⟩ ∈ (On × On)))
8		df-lexo 35921	. . . 4 ⊢ LexOrd = {⟨𝑥, 𝑦⟩ ∣ ((𝑥 ∈ (On × On) ∧ 𝑦 ∈ (On × On)) ∧ ((1st ‘𝑥) ∈ (1st ‘𝑦) ∨ ((1st ‘𝑥) = (1st ‘𝑦) ∧ (2nd ‘𝑥) ∈ (2nd ‘𝑦))))}
9	8	a1i 11	. . 3 ⊢ (𝜑 → LexOrd = {⟨𝑥, 𝑦⟩ ∣ ((𝑥 ∈ (On × On) ∧ 𝑦 ∈ (On × On)) ∧ ((1st ‘𝑥) ∈ (1st ‘𝑦) ∨ ((1st ‘𝑥) = (1st ‘𝑦) ∧ (2nd ‘𝑥) ∈ (2nd ‘𝑦))))})
10		fveq2 6885	. . . . . . 7 ⊢ (𝑥 = ⟨𝐴, 𝐵⟩ → (1st ‘𝑥) = (1st ‘⟨𝐴, 𝐵⟩))
11		op1stg 8013	. . . . . . . 8 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (1st ‘⟨𝐴, 𝐵⟩) = 𝐴)
12	1, 2, 11	syl2anc 596	. . . . . . 7 ⊢ (𝜑 → (1st ‘⟨𝐴, 𝐵⟩) = 𝐴)
13	10, 12	sylan9eqr 2817	. . . . . 6 ⊢ ((𝜑 ∧ 𝑥 = ⟨𝐴, 𝐵⟩) → (1st ‘𝑥) = 𝐴)
14	13	adantrr 730	. . . . 5 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → (1st ‘𝑥) = 𝐴)
15		fveq2 6885	. . . . . . 7 ⊢ (𝑦 = ⟨𝐶, 𝐷⟩ → (1st ‘𝑦) = (1st ‘⟨𝐶, 𝐷⟩))
16		op1stg 8013	. . . . . . . 8 ⊢ ((𝐶 ∈ On ∧ 𝐷 ∈ On) → (1st ‘⟨𝐶, 𝐷⟩) = 𝐶)
17	4, 5, 16	syl2anc 596	. . . . . . 7 ⊢ (𝜑 → (1st ‘⟨𝐶, 𝐷⟩) = 𝐶)
18	15, 17	sylan9eqr 2817	. . . . . 6 ⊢ ((𝜑 ∧ 𝑦 = ⟨𝐶, 𝐷⟩) → (1st ‘𝑦) = 𝐶)
19	18	adantrl 729	. . . . 5 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → (1st ‘𝑦) = 𝐶)
20	14, 19	eleq12d 2854	. . . 4 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → ((1st ‘𝑥) ∈ (1st ‘𝑦) ↔ 𝐴 ∈ 𝐶))
21	14, 19	eqeq12d 2776	. . . . 5 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → ((1st ‘𝑥) = (1st ‘𝑦) ↔ 𝐴 = 𝐶))
22		fveq2 6885	. . . . . . . 8 ⊢ (𝑥 = ⟨𝐴, 𝐵⟩ → (2nd ‘𝑥) = (2nd ‘⟨𝐴, 𝐵⟩))
23		op2ndg 8014	. . . . . . . . 9 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (2nd ‘⟨𝐴, 𝐵⟩) = 𝐵)
24	1, 2, 23	syl2anc 596	. . . . . . . 8 ⊢ (𝜑 → (2nd ‘⟨𝐴, 𝐵⟩) = 𝐵)
25	22, 24	sylan9eqr 2817	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑥 = ⟨𝐴, 𝐵⟩) → (2nd ‘𝑥) = 𝐵)
26	25	adantrr 730	. . . . . 6 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → (2nd ‘𝑥) = 𝐵)
27		fveq2 6885	. . . . . . . 8 ⊢ (𝑦 = ⟨𝐶, 𝐷⟩ → (2nd ‘𝑦) = (2nd ‘⟨𝐶, 𝐷⟩))
28		op2ndg 8014	. . . . . . . . 9 ⊢ ((𝐶 ∈ On ∧ 𝐷 ∈ On) → (2nd ‘⟨𝐶, 𝐷⟩) = 𝐷)
29	4, 5, 28	syl2anc 596	. . . . . . . 8 ⊢ (𝜑 → (2nd ‘⟨𝐶, 𝐷⟩) = 𝐷)
30	27, 29	sylan9eqr 2817	. . . . . . 7 ⊢ ((𝜑 ∧ 𝑦 = ⟨𝐶, 𝐷⟩) → (2nd ‘𝑦) = 𝐷)
31	30	adantrl 729	. . . . . 6 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → (2nd ‘𝑦) = 𝐷)
32	26, 31	eleq12d 2854	. . . . 5 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → ((2nd ‘𝑥) ∈ (2nd ‘𝑦) ↔ 𝐵 ∈ 𝐷))
33	21, 32	anbi12d 644	. . . 4 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → (((1st ‘𝑥) = (1st ‘𝑦) ∧ (2nd ‘𝑥) ∈ (2nd ‘𝑦)) ↔ (𝐴 = 𝐶 ∧ 𝐵 ∈ 𝐷)))
34	20, 33	orbi12d 932	. . 3 ⊢ ((𝜑 ∧ (𝑥 = ⟨𝐴, 𝐵⟩ ∧ 𝑦 = ⟨𝐶, 𝐷⟩)) → (((1st ‘𝑥) ∈ (1st ‘𝑦) ∨ ((1st ‘𝑥) = (1st ‘𝑦) ∧ (2nd ‘𝑥) ∈ (2nd ‘𝑦))) ↔ (𝐴 ∈ 𝐶 ∨ (𝐴 = 𝐶 ∧ 𝐵 ∈ 𝐷))))
35	9, 34	brab2d 5511	. 2 ⊢ (𝜑 → (⟨𝐴, 𝐵⟩LexOrd⟨𝐶, 𝐷⟩ ↔ ((⟨𝐴, 𝐵⟩ ∈ (On × On) ∧ ⟨𝐶, 𝐷⟩ ∈ (On × On)) ∧ (𝐴 ∈ 𝐶 ∨ (𝐴 = 𝐶 ∧ 𝐵 ∈ 𝐷)))))
36	7, 35	mpbirand 720	1 ⊢ (𝜑 → (⟨𝐴, 𝐵⟩LexOrd⟨𝐶, 𝐷⟩ ↔ (𝐴 ∈ 𝐶 ∨ (𝐴 = 𝐶 ∧ 𝐵 ∈ 𝐷))))

This proof depends on syntax axioms:   → wi 4   ↔ wb 209   ∧ wa 401   ∨ wo 861   = wceq 1569   ∈ wcel 2144  ⟨cop 4589   class class class wbr 5102  {copab 5166   × cxp 5648  Oncon0 6362  ‘cfv 6538  1^st c1st 7999  2^nd c2nd 8000  LexOrdclexo 35912

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1942  ax-6 1999  ax-7 2040  ax-8 2146  ax-9 2154  ax-10 2177  ax-11 2193  ax-12 2212  ax-ext 2732  ax-sep 5248  ax-nul 5259  ax-pr 5390  ax-un 7751

This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3an 1105  df-tru 1572  df-fal 1582  df-ex 1812  df-nf 1816  df-sb 2099  df-mo 2564  df-eu 2594  df-clab 2739  df-cleq 2752  df-clel 2835  df-nfc 2909  df-ne 2956  df-ral 3077  df-rex 3087  df-rab 3413  df-v 3452  df-ss 3896  df-dif 4047  df-in 4091  df-un 4151  df-nul 4279  df-if 4482  df-sn 4584  df-pr 4586  df-op 4590  df-uni 4867  df-br 5103  df-opab 5167  df-mpt 5186  df-id 5545  df-xp 5656  df-rel 5657  df-cnv 5658  df-co 5659  df-dm 5660  df-rn 5661  df-iota 6494  df-fun 6540  df-fv 6546  df-1st 8001  df-2nd 8002  df-lexo 35921

This theorem is used by:  maxssj0  35938