Proof of Theorem onntri45
| Step | Hyp | Ref
 | Expression | 
| 1 |   | pw1on 7293 | 
. . . . 5
⊢ 𝒫
1o ∈ On | 
| 2 | 1 | onsuci 4552 | 
. . . 4
⊢ suc
𝒫 1o ∈ On | 
| 3 |   | 3on 6485 | 
. . . 4
⊢
3o ∈ On | 
| 4 |   | sseq1 3206 | 
. . . . . . . 8
⊢ (𝑥 = suc 𝒫 1o
→ (𝑥 ⊆ 𝑦 ↔ suc 𝒫
1o ⊆ 𝑦)) | 
| 5 |   | sseq2 3207 | 
. . . . . . . 8
⊢ (𝑥 = suc 𝒫 1o
→ (𝑦 ⊆ 𝑥 ↔ 𝑦 ⊆ suc 𝒫
1o)) | 
| 6 | 4, 5 | orbi12d 794 | 
. . . . . . 7
⊢ (𝑥 = suc 𝒫 1o
→ ((𝑥 ⊆ 𝑦 ∨ 𝑦 ⊆ 𝑥) ↔ (suc 𝒫 1o ⊆
𝑦 ∨ 𝑦 ⊆ suc 𝒫
1o))) | 
| 7 | 6 | notbid 668 | 
. . . . . 6
⊢ (𝑥 = suc 𝒫 1o
→ (¬ (𝑥 ⊆
𝑦 ∨ 𝑦 ⊆ 𝑥) ↔ ¬ (suc 𝒫 1o
⊆ 𝑦 ∨ 𝑦 ⊆ suc 𝒫
1o))) | 
| 8 | 7 | notbid 668 | 
. . . . 5
⊢ (𝑥 = suc 𝒫 1o
→ (¬ ¬ (𝑥
⊆ 𝑦 ∨ 𝑦 ⊆ 𝑥) ↔ ¬ ¬ (suc 𝒫
1o ⊆ 𝑦
∨ 𝑦 ⊆ suc
𝒫 1o))) | 
| 9 |   | sseq2 3207 | 
. . . . . . . 8
⊢ (𝑦 = 3o → (suc
𝒫 1o ⊆ 𝑦 ↔ suc 𝒫 1o ⊆
3o)) | 
| 10 |   | sseq1 3206 | 
. . . . . . . 8
⊢ (𝑦 = 3o → (𝑦 ⊆ suc 𝒫
1o ↔ 3o ⊆ suc 𝒫
1o)) | 
| 11 | 9, 10 | orbi12d 794 | 
. . . . . . 7
⊢ (𝑦 = 3o → ((suc
𝒫 1o ⊆ 𝑦 ∨ 𝑦 ⊆ suc 𝒫 1o) ↔
(suc 𝒫 1o ⊆ 3o ∨ 3o ⊆
suc 𝒫 1o))) | 
| 12 | 11 | notbid 668 | 
. . . . . 6
⊢ (𝑦 = 3o → (¬
(suc 𝒫 1o ⊆ 𝑦 ∨ 𝑦 ⊆ suc 𝒫 1o) ↔
¬ (suc 𝒫 1o ⊆ 3o ∨ 3o
⊆ suc 𝒫 1o))) | 
| 13 | 12 | notbid 668 | 
. . . . 5
⊢ (𝑦 = 3o → (¬
¬ (suc 𝒫 1o ⊆ 𝑦 ∨ 𝑦 ⊆ suc 𝒫 1o) ↔
¬ ¬ (suc 𝒫 1o ⊆ 3o ∨
3o ⊆ suc 𝒫 1o))) | 
| 14 | 8, 13 | rspc2v 2881 | 
. . . 4
⊢ ((suc
𝒫 1o ∈ On ∧ 3o ∈ On) →
(∀𝑥 ∈ On
∀𝑦 ∈ On ¬
¬ (𝑥 ⊆ 𝑦 ∨ 𝑦 ⊆ 𝑥) → ¬ ¬ (suc 𝒫
1o ⊆ 3o ∨ 3o ⊆ suc 𝒫
1o))) | 
| 15 | 2, 3, 14 | mp2an 426 | 
. . 3
⊢
(∀𝑥 ∈ On
∀𝑦 ∈ On ¬
¬ (𝑥 ⊆ 𝑦 ∨ 𝑦 ⊆ 𝑥) → ¬ ¬ (suc 𝒫
1o ⊆ 3o ∨ 3o ⊆ suc 𝒫
1o)) | 
| 16 |   | ioran 753 | 
. . 3
⊢ (¬
(suc 𝒫 1o ⊆ 3o ∨ 3o ⊆
suc 𝒫 1o) ↔ (¬ suc 𝒫 1o ⊆
3o ∧ ¬ 3o ⊆ suc 𝒫
1o)) | 
| 17 | 15, 16 | sylnib 677 | 
. 2
⊢
(∀𝑥 ∈ On
∀𝑦 ∈ On ¬
¬ (𝑥 ⊆ 𝑦 ∨ 𝑦 ⊆ 𝑥) → ¬ (¬ suc 𝒫
1o ⊆ 3o ∧ ¬ 3o ⊆ suc
𝒫 1o)) | 
| 18 |   | sucpw1nss3 7302 | 
. . 3
⊢ (¬
EXMID → ¬ suc 𝒫 1o ⊆
3o) | 
| 19 |   | 3nsssucpw1 7303 | 
. . 3
⊢ (¬
EXMID → ¬ 3o ⊆ suc 𝒫
1o) | 
| 20 | 18, 19 | jca 306 | 
. 2
⊢ (¬
EXMID → (¬ suc 𝒫 1o ⊆
3o ∧ ¬ 3o ⊆ suc 𝒫
1o)) | 
| 21 | 17, 20 | nsyl 629 | 
1
⊢
(∀𝑥 ∈ On
∀𝑦 ∈ On ¬
¬ (𝑥 ⊆ 𝑦 ∨ 𝑦 ⊆ 𝑥) → ¬ ¬
EXMID) |