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Theorem ordtri3 6342

Description: A trichotomy law for ordinals. (Contributed by NM, 18-Oct-1995.) (Proof shortened by Andrew Salmon, 25-Jul-2011.) (Proof shortened by JJ, 24-Sep-2021.)

**Assertion**
Ref	Expression
ordtri3	⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (𝐴 = 𝐵 ↔ ¬ (𝐴 ∈ 𝐵 ∨ 𝐵 ∈ 𝐴)))

**Proof of Theorem ordtri3**
Step	Hyp	Ref	Expression
1		ordirr 6324	. . . . . 6 ⊢ (Ord 𝐵 → ¬ 𝐵 ∈ 𝐵)
2	1	adantl 481	. . . . 5 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → ¬ 𝐵 ∈ 𝐵)
3		eleq2 2820	. . . . . 6 ⊢ (𝐴 = 𝐵 → (𝐵 ∈ 𝐴 ↔ 𝐵 ∈ 𝐵))
4	3	notbid 318	. . . . 5 ⊢ (𝐴 = 𝐵 → (¬ 𝐵 ∈ 𝐴 ↔ ¬ 𝐵 ∈ 𝐵))
5	2, 4	syl5ibrcom 247	. . . 4 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (𝐴 = 𝐵 → ¬ 𝐵 ∈ 𝐴))
6	5	pm4.71d 561	. . 3 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (𝐴 = 𝐵 ↔ (𝐴 = 𝐵 ∧ ¬ 𝐵 ∈ 𝐴)))
7		pm5.61 1002	. . . 4 ⊢ (((𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∧ ¬ 𝐵 ∈ 𝐴) ↔ (𝐴 = 𝐵 ∧ ¬ 𝐵 ∈ 𝐴))
8		pm4.52 986	. . . 4 ⊢ (((𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∧ ¬ 𝐵 ∈ 𝐴) ↔ ¬ (¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∨ 𝐵 ∈ 𝐴))
9	7, 8	bitr3i 277	. . 3 ⊢ ((𝐴 = 𝐵 ∧ ¬ 𝐵 ∈ 𝐴) ↔ ¬ (¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∨ 𝐵 ∈ 𝐴))
10	6, 9	bitrdi 287	. 2 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (𝐴 = 𝐵 ↔ ¬ (¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∨ 𝐵 ∈ 𝐴)))
11		ordtri2 6341	. . . 4 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (𝐴 ∈ 𝐵 ↔ ¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴)))
12	11	orbi1d 916	. . 3 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → ((𝐴 ∈ 𝐵 ∨ 𝐵 ∈ 𝐴) ↔ (¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∨ 𝐵 ∈ 𝐴)))
13	12	notbid 318	. 2 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (¬ (𝐴 ∈ 𝐵 ∨ 𝐵 ∈ 𝐴) ↔ ¬ (¬ (𝐴 = 𝐵 ∨ 𝐵 ∈ 𝐴) ∨ 𝐵 ∈ 𝐴)))
14	10, 13	bitr4d 282	1 ⊢ ((Ord 𝐴 ∧ Ord 𝐵) → (𝐴 = 𝐵 ↔ ¬ (𝐴 ∈ 𝐵 ∨ 𝐵 ∈ 𝐴)))

Colors of variables: wff setvar class

Syntax hints: ¬ wn 3 → wi 4 ↔ wb 206 ∧ wa 395 ∨ wo 847 = wceq 1541 ∈ wcel 2111 Ord word 6305

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1968 ax-7 2009 ax-8 2113 ax-9 2121 ax-ext 2703 ax-sep 5232 ax-nul 5242 ax-pr 5368

This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3or 1087 df-3an 1088 df-tru 1544 df-fal 1554 df-ex 1781 df-sb 2068 df-clab 2710 df-cleq 2723 df-clel 2806 df-ne 2929 df-ral 3048 df-rex 3057 df-rab 3396 df-v 3438 df-dif 3900 df-un 3902 df-in 3904 df-ss 3914 df-pss 3917 df-nul 4281 df-if 4473 df-pw 4549 df-sn 4574 df-pr 4576 df-op 4580 df-uni 4857 df-br 5090 df-opab 5152 df-tr 5197 df-eprel 5514 df-po 5522 df-so 5523 df-fr 5567 df-we 5569 df-ord 6309

This theorem is referenced by: ordunisuc2 7774 tz7.48lem 8360 oacan 8463 omcan 8484 oecan 8504 omsmo 8573 omopthi 8576 inf3lem6 9523 cantnfp1lem3 9570 infpssrlem5 10198 fin23lem24 10213 isf32lem4 10247 om2uzf1oi 13860 om2noseqf1o 28231 ordnexbtwnsuc 43370

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