Proof of Theorem oaordex
Step | Hyp | Ref
| Expression |
1 | | onelss 6301 |
. . . . 5
⊢ (𝐵 ∈ On → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) |
2 | 1 | adantl 482 |
. . . 4
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ∈ 𝐵 → 𝐴 ⊆ 𝐵)) |
3 | | oawordex 8375 |
. . . 4
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ⊆ 𝐵 ↔ ∃𝑥 ∈ On (𝐴 +o 𝑥) = 𝐵)) |
4 | 2, 3 | sylibd 238 |
. . 3
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ∈ 𝐵 → ∃𝑥 ∈ On (𝐴 +o 𝑥) = 𝐵)) |
5 | | oaord1 8369 |
. . . . . . . . . . . . 13
⊢ ((𝐴 ∈ On ∧ 𝑥 ∈ On) → (∅
∈ 𝑥 ↔ 𝐴 ∈ (𝐴 +o 𝑥))) |
6 | | eleq2 2827 |
. . . . . . . . . . . . 13
⊢ ((𝐴 +o 𝑥) = 𝐵 → (𝐴 ∈ (𝐴 +o 𝑥) ↔ 𝐴 ∈ 𝐵)) |
7 | 5, 6 | sylan9bb 510 |
. . . . . . . . . . . 12
⊢ (((𝐴 ∈ On ∧ 𝑥 ∈ On) ∧ (𝐴 +o 𝑥) = 𝐵) → (∅ ∈ 𝑥 ↔ 𝐴 ∈ 𝐵)) |
8 | 7 | biimprcd 249 |
. . . . . . . . . . 11
⊢ (𝐴 ∈ 𝐵 → (((𝐴 ∈ On ∧ 𝑥 ∈ On) ∧ (𝐴 +o 𝑥) = 𝐵) → ∅ ∈ 𝑥)) |
9 | 8 | exp4c 433 |
. . . . . . . . . 10
⊢ (𝐴 ∈ 𝐵 → (𝐴 ∈ On → (𝑥 ∈ On → ((𝐴 +o 𝑥) = 𝐵 → ∅ ∈ 𝑥)))) |
10 | 9 | com12 32 |
. . . . . . . . 9
⊢ (𝐴 ∈ On → (𝐴 ∈ 𝐵 → (𝑥 ∈ On → ((𝐴 +o 𝑥) = 𝐵 → ∅ ∈ 𝑥)))) |
11 | 10 | imp4b 422 |
. . . . . . . 8
⊢ ((𝐴 ∈ On ∧ 𝐴 ∈ 𝐵) → ((𝑥 ∈ On ∧ (𝐴 +o 𝑥) = 𝐵) → ∅ ∈ 𝑥)) |
12 | | simpr 485 |
. . . . . . . 8
⊢ ((𝑥 ∈ On ∧ (𝐴 +o 𝑥) = 𝐵) → (𝐴 +o 𝑥) = 𝐵) |
13 | 11, 12 | jca2 514 |
. . . . . . 7
⊢ ((𝐴 ∈ On ∧ 𝐴 ∈ 𝐵) → ((𝑥 ∈ On ∧ (𝐴 +o 𝑥) = 𝐵) → (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵))) |
14 | 13 | expd 416 |
. . . . . 6
⊢ ((𝐴 ∈ On ∧ 𝐴 ∈ 𝐵) → (𝑥 ∈ On → ((𝐴 +o 𝑥) = 𝐵 → (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵)))) |
15 | 14 | reximdvai 3198 |
. . . . 5
⊢ ((𝐴 ∈ On ∧ 𝐴 ∈ 𝐵) → (∃𝑥 ∈ On (𝐴 +o 𝑥) = 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵))) |
16 | 15 | ex 413 |
. . . 4
⊢ (𝐴 ∈ On → (𝐴 ∈ 𝐵 → (∃𝑥 ∈ On (𝐴 +o 𝑥) = 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵)))) |
17 | 16 | adantr 481 |
. . 3
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ∈ 𝐵 → (∃𝑥 ∈ On (𝐴 +o 𝑥) = 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵)))) |
18 | 4, 17 | mpdd 43 |
. 2
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ∈ 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵))) |
19 | 7 | biimpd 228 |
. . . . . . 7
⊢ (((𝐴 ∈ On ∧ 𝑥 ∈ On) ∧ (𝐴 +o 𝑥) = 𝐵) → (∅ ∈ 𝑥 → 𝐴 ∈ 𝐵)) |
20 | 19 | exp31 420 |
. . . . . 6
⊢ (𝐴 ∈ On → (𝑥 ∈ On → ((𝐴 +o 𝑥) = 𝐵 → (∅ ∈ 𝑥 → 𝐴 ∈ 𝐵)))) |
21 | 20 | com34 91 |
. . . . 5
⊢ (𝐴 ∈ On → (𝑥 ∈ On → (∅
∈ 𝑥 → ((𝐴 +o 𝑥) = 𝐵 → 𝐴 ∈ 𝐵)))) |
22 | 21 | imp4a 423 |
. . . 4
⊢ (𝐴 ∈ On → (𝑥 ∈ On → ((∅
∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵) → 𝐴 ∈ 𝐵))) |
23 | 22 | rexlimdv 3210 |
. . 3
⊢ (𝐴 ∈ On → (∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵) → 𝐴 ∈ 𝐵)) |
24 | 23 | adantr 481 |
. 2
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵) → 𝐴 ∈ 𝐵)) |
25 | 18, 24 | impbid 211 |
1
⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 ∈ 𝐵 ↔ ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +o 𝑥) = 𝐵))) |