Proof of Theorem ordtri3
| Step | Hyp | Ref
| Expression |
| 1 | | eleq2 1150 |
. . . . . . 7
⊢ (A =
B → (A ∈ A
↔ A ∈ B)) |
| 2 | 1 | negbid 463 |
. . . . . 6
⊢ (A =
B → (¬ A ∈ A
↔ ¬ A ∈ B)) |
| 3 | | ordeirr 2217 |
. . . . . 6
⊢ (Ord A
→ ¬ A ∈ A) |
| 4 | 2, 3 | syl5bi 183 |
. . . . 5
⊢ (A =
B → (Ord A → ¬ A
∈ B)) |
| 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 | 4, 8 | anim12d 431 |
. . . 4
⊢ (A =
B → ((Ord A ∧ Ord B)
→ (¬ A ∈ B ∧ ¬ B
∈ A))) |
| 10 | | ioran 254 |
. . . 4
⊢ (¬ (A ∈ B ∨
B ∈ A) ↔ (¬ A ∈ B ∧
¬ B ∈ A)) |
| 11 | 9, 10 | syl6ibr 186 |
. . 3
⊢ (A =
B → ((Ord A ∧ Ord B)
→ ¬ (A ∈ B ∨ B ∈
A))) |
| 12 | 11 | com12 13 |
. 2
⊢ ((Ord A ∧ Ord B)
→ (A = B → ¬ (A ∈ B ∨
B ∈ A))) |
| 13 | | ordtri3or 2230 |
. . 3
⊢ ((Ord A ∧ Ord B)
→ (A ∈ B ∨ A =
B ∨ B ∈ A)) |
| 14 | | df-3or 582 |
. . . 4
⊢ ((A
∈ B ∨ A = B ∨
B ∈ A) ↔ ((A
∈ B ∨ A = B) ∨
B ∈ A)) |
| 15 | | or23 219 |
. . . 4
⊢ (((A
∈ B ∨ A = B) ∨
B ∈ A) ↔ ((A
∈ B ∨ B ∈ A) ∨
A = B)) |
| 16 | | df-or 197 |
. . . 4
⊢ (((A
∈ B ∨ B ∈ A) ∨
A = B)
↔ (¬ (A ∈ B ∨ B ∈
A) → A = B)) |
| 17 | 14, 15, 16 | 3bitr 155 |
. . 3
⊢ ((A
∈ B ∨ A = B ∨
B ∈ A) ↔ (¬ (A ∈ B ∨
B ∈ A) → A =
B)) |
| 18 | 13, 17 | sylib 173 |
. 2
⊢ ((Ord A ∧ Ord B)
→ (¬ (A ∈ B ∨ B ∈
A) → A = B)) |
| 19 | 12, 18 | impbid 397 |
1
⊢ ((Ord A ∧ Ord B)
→ (A = B ↔ ¬ (A ∈ B ∨
B ∈ A))) |