Proof of Theorem ordtri1
| Step | Hyp | Ref
| Expression |
| 1 | | ordsseleq 2227 |
. 2
⊢ ((Ord A ∧ Ord B)
→ (A ⊆ B ↔ (A
∈ B ∨ A = B))) |
| 2 | | ordn2lp 2219 |
. . . . 5
⊢ (Ord A
→ ¬ (A ∈ B ∧ B ∈
A)) |
| 3 | | imnan 207 |
. . . . 5
⊢ ((A
∈ B → ¬ B ∈ A)
↔ ¬ (A ∈ B ∧ B ∈
A)) |
| 4 | 2, 3 | sylibr 175 |
. . . 4
⊢ (Ord A
→ (A ∈ B → ¬ B
∈ A)) |
| 5 | | eleq2 1150 |
. . . . . . 7
⊢ (A =
B → (B ∈ A
↔ B ∈ B)) |
| 6 | 5 | negbid 463 |
. . . . . 6
⊢ (A =
B → (¬ B ∈ A
↔ ¬ B ∈ B)) |
| 7 | | ordeirr 2217 |
. . . . . 6
⊢ (Ord B
→ ¬ B ∈ B) |
| 8 | 6, 7 | syl5bir 184 |
. . . . 5
⊢ (A =
B → (Ord B → ¬ B
∈ A)) |
| 9 | 8 | com12 13 |
. . . 4
⊢ (Ord B
→ (A = B → ¬ B
∈ A)) |
| 10 | 4, 9 | jaao 330 |
. . 3
⊢ ((Ord A ∧ Ord B)
→ ((A ∈ B ∨ A =
B) → ¬ B ∈ A)) |
| 11 | | ordtri3or 2230 |
. . . 4
⊢ ((Ord A ∧ Ord B)
→ (A ∈ B ∨ A =
B ∨ B ∈ A)) |
| 12 | | df-3or 582 |
. . . . 5
⊢ ((A
∈ B ∨ A = B ∨
B ∈ A) ↔ ((A
∈ B ∨ A = B) ∨
B ∈ A)) |
| 13 | | orcom 209 |
. . . . 5
⊢ (((A
∈ B ∨ A = B) ∨
B ∈ A) ↔ (B
∈ A ∨ (A ∈ B ∨
A = B))) |
| 14 | | df-or 197 |
. . . . 5
⊢ ((B
∈ A ∨ (A ∈ B ∨
A = B))
↔ (¬ B ∈ A → (A
∈ B ∨ A = B))) |
| 15 | 12, 13, 14 | 3bitr 155 |
. . . 4
⊢ ((A
∈ B ∨ A = B ∨
B ∈ A) ↔ (¬ B ∈ A
→ (A ∈ B ∨ A =
B))) |
| 16 | 11, 15 | sylib 173 |
. . 3
⊢ ((Ord A ∧ Ord B)
→ (¬ B ∈ A → (A
∈ B ∨ A = B))) |
| 17 | 10, 16 | impbid 397 |
. 2
⊢ ((Ord A ∧ Ord B)
→ ((A ∈ B ∨ A =
B) ↔ ¬ B ∈ A)) |
| 18 | 1, 17 | bitrd 406 |
1
⊢ ((Ord A ∧ Ord B)
→ (A ⊆ B ↔ ¬ B
∈ A)) |