| Step | Hyp | Ref
 | Expression | 
| 1 |   | elirrv 4584 | 
. . . . . 6
⊢  ¬
𝑥 ∈ 𝑥 | 
| 2 |   | ltpiord 7386 | 
. . . . . . 7
⊢ ((𝑥 ∈ N ∧
𝑥 ∈ N)
→ (𝑥
<N 𝑥 ↔ 𝑥 ∈ 𝑥)) | 
| 3 | 2 | anidms 397 | 
. . . . . 6
⊢ (𝑥 ∈ N →
(𝑥
<N 𝑥 ↔ 𝑥 ∈ 𝑥)) | 
| 4 | 1, 3 | mtbiri 676 | 
. . . . 5
⊢ (𝑥 ∈ N →
¬ 𝑥
<N 𝑥) | 
| 5 | 4 | adantl 277 | 
. . . 4
⊢
((⊤ ∧ 𝑥
∈ N) → ¬ 𝑥 <N 𝑥) | 
| 6 |   | pion 7377 | 
. . . . . . . 8
⊢ (𝑧 ∈ N →
𝑧 ∈
On) | 
| 7 |   | ontr1 4424 | 
. . . . . . . 8
⊢ (𝑧 ∈ On → ((𝑥 ∈ 𝑦 ∧ 𝑦 ∈ 𝑧) → 𝑥 ∈ 𝑧)) | 
| 8 | 6, 7 | syl 14 | 
. . . . . . 7
⊢ (𝑧 ∈ N →
((𝑥 ∈ 𝑦 ∧ 𝑦 ∈ 𝑧) → 𝑥 ∈ 𝑧)) | 
| 9 | 8 | 3ad2ant3 1022 | 
. . . . . 6
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N
∧ 𝑧 ∈
N) → ((𝑥
∈ 𝑦 ∧ 𝑦 ∈ 𝑧) → 𝑥 ∈ 𝑧)) | 
| 10 |   | ltpiord 7386 | 
. . . . . . . 8
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N)
→ (𝑥
<N 𝑦 ↔ 𝑥 ∈ 𝑦)) | 
| 11 | 10 | 3adant3 1019 | 
. . . . . . 7
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N
∧ 𝑧 ∈
N) → (𝑥
<N 𝑦 ↔ 𝑥 ∈ 𝑦)) | 
| 12 |   | ltpiord 7386 | 
. . . . . . . 8
⊢ ((𝑦 ∈ N ∧
𝑧 ∈ N)
→ (𝑦
<N 𝑧 ↔ 𝑦 ∈ 𝑧)) | 
| 13 | 12 | 3adant1 1017 | 
. . . . . . 7
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N
∧ 𝑧 ∈
N) → (𝑦
<N 𝑧 ↔ 𝑦 ∈ 𝑧)) | 
| 14 | 11, 13 | anbi12d 473 | 
. . . . . 6
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N
∧ 𝑧 ∈
N) → ((𝑥
<N 𝑦 ∧ 𝑦 <N 𝑧) ↔ (𝑥 ∈ 𝑦 ∧ 𝑦 ∈ 𝑧))) | 
| 15 |   | ltpiord 7386 | 
. . . . . . 7
⊢ ((𝑥 ∈ N ∧
𝑧 ∈ N)
→ (𝑥
<N 𝑧 ↔ 𝑥 ∈ 𝑧)) | 
| 16 | 15 | 3adant2 1018 | 
. . . . . 6
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N
∧ 𝑧 ∈
N) → (𝑥
<N 𝑧 ↔ 𝑥 ∈ 𝑧)) | 
| 17 | 9, 14, 16 | 3imtr4d 203 | 
. . . . 5
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N
∧ 𝑧 ∈
N) → ((𝑥
<N 𝑦 ∧ 𝑦 <N 𝑧) → 𝑥 <N 𝑧)) | 
| 18 | 17 | adantl 277 | 
. . . 4
⊢
((⊤ ∧ (𝑥
∈ N ∧ 𝑦 ∈ N ∧ 𝑧 ∈ N)) →
((𝑥
<N 𝑦 ∧ 𝑦 <N 𝑧) → 𝑥 <N 𝑧)) | 
| 19 | 5, 18 | ispod 4339 | 
. . 3
⊢ (⊤
→ <N Po N) | 
| 20 |   | pinn 7376 | 
. . . . . 6
⊢ (𝑥 ∈ N →
𝑥 ∈
ω) | 
| 21 |   | pinn 7376 | 
. . . . . 6
⊢ (𝑦 ∈ N →
𝑦 ∈
ω) | 
| 22 |   | nntri3or 6551 | 
. . . . . 6
⊢ ((𝑥 ∈ ω ∧ 𝑦 ∈ ω) → (𝑥 ∈ 𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 ∈ 𝑥)) | 
| 23 | 20, 21, 22 | syl2an 289 | 
. . . . 5
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N)
→ (𝑥 ∈ 𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 ∈ 𝑥)) | 
| 24 |   | biidd 172 | 
. . . . . 6
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N)
→ (𝑥 = 𝑦 ↔ 𝑥 = 𝑦)) | 
| 25 |   | ltpiord 7386 | 
. . . . . . 7
⊢ ((𝑦 ∈ N ∧
𝑥 ∈ N)
→ (𝑦
<N 𝑥 ↔ 𝑦 ∈ 𝑥)) | 
| 26 | 25 | ancoms 268 | 
. . . . . 6
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N)
→ (𝑦
<N 𝑥 ↔ 𝑦 ∈ 𝑥)) | 
| 27 | 10, 24, 26 | 3orbi123d 1322 | 
. . . . 5
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N)
→ ((𝑥
<N 𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 <N 𝑥) ↔ (𝑥 ∈ 𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 ∈ 𝑥))) | 
| 28 | 23, 27 | mpbird 167 | 
. . . 4
⊢ ((𝑥 ∈ N ∧
𝑦 ∈ N)
→ (𝑥
<N 𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 <N 𝑥)) | 
| 29 | 28 | adantl 277 | 
. . 3
⊢
((⊤ ∧ (𝑥
∈ N ∧ 𝑦 ∈ N)) → (𝑥 <N
𝑦 ∨ 𝑥 = 𝑦 ∨ 𝑦 <N 𝑥)) | 
| 30 | 19, 29 | issod 4354 | 
. 2
⊢ (⊤
→ <N Or N) | 
| 31 | 30 | mptru 1373 | 
1
⊢ 
<N Or N |