Proof of Theorem alephord3
| Step | Hyp | Ref
| Expression |
| 1 | | alephord2 3681 |
. . . 4
⊢ ((B
∈ On ∧ A ∈ On) →
(B ∈ A ↔ (ℵ ‘B) ∈ (ℵ ‘A))) |
| 2 | 1 | ancoms 334 |
. . 3
⊢ ((A
∈ On ∧ B ∈ On) →
(B ∈ A ↔ (ℵ ‘B) ∈ (ℵ ‘A))) |
| 3 | 2 | negbid 463 |
. 2
⊢ ((A
∈ On ∧ B ∈ On) → (¬
B ∈ A ↔ ¬ (ℵ ‘B) ∈ (ℵ ‘A))) |
| 4 | | ontri1 2232 |
. 2
⊢ ((A
∈ On ∧ B ∈ On) →
(A ⊆ B ↔ ¬ B
∈ A)) |
| 5 | | alephon 3671 |
. . . 4
⊢ (ℵ ‘A) ∈ On |
| 6 | | alephon 3671 |
. . . 4
⊢ (ℵ ‘B) ∈ On |
| 7 | | ontri1 2232 |
. . . 4
⊢ (((ℵ ‘A) ∈ On ∧ (ℵ ‘B) ∈ On) → ((ℵ ‘A) ⊆ (ℵ ‘B) ↔ ¬ (ℵ ‘B) ∈ (ℵ ‘A))) |
| 8 | 5, 6, 7 | mp2an 520 |
. . 3
⊢ ((ℵ ‘A) ⊆ (ℵ ‘B) ↔ ¬ (ℵ ‘B) ∈ (ℵ ‘A)) |
| 9 | 8 | a1i 7 |
. 2
⊢ ((A
∈ On ∧ B ∈ On) →
((ℵ ‘A) ⊆ (ℵ
‘B) ↔ ¬ (ℵ
‘B) ∈ (ℵ ‘A))) |
| 10 | 3, 4, 9 | 3bitr4d 424 |
1
⊢ ((A
∈ On ∧ B ∈ On) →
(A ⊆ B ↔ (ℵ & |