Proof of Theorem nnawordex
| Step | Hyp | Ref
| Expression |
| 1 | | oawordex 3159 |
. . . 4
⊢ ((A
∈ On ∧ B ∈ On) →
(A ⊆ B ↔ ∃x ∈ On (A
+o x) = B)) |
| 2 | | nnont 2379 |
. . . 4
⊢ (B
∈ ω → B ∈
On) |
| 3 | 1, 2 | sylan2 346 |
. . 3
⊢ ((A
∈ On ∧ B ∈ ω) →
(A ⊆ B ↔ ∃x ∈ On (A
+o x) = B)) |
| 4 | | eleq1 1149 |
. . . . . . . . . . . . 13
⊢ ((A
+o x) = B → ((A
+o x) ∈ ω
↔ B ∈ ω)) |
| 5 | 4 | bicomd 399 |
. . . . . . . . . . . 12
⊢ ((A
+o x) = B → (B
∈ ω ↔ (A
+o x) ∈
ω)) |
| 6 | | nnarcl 3174 |
. . . . . . . . . . . 12
⊢ ((A
∈ On ∧ x ∈ On) →
((A +o x) ∈ ω ↔ (A ∈ ω ∧ x ∈ ω))) |
| 7 | 5, 6 | sylan9bbr 419 |
. . . . . . . . . . 11
⊢ (((A
∈ On ∧ x ∈ On) ∧
(A +o x) = B) →
(B ∈ ω ↔ (A ∈ ω ∧ x ∈ ω))) |
| 8 | | pm3.27 260 |
. . . . . . . . . . 11
⊢ ((A
∈ ω ∧ x ∈ ω)
→ x ∈ ω) |
| 9 | 7, 8 | syl6bi 187 |
. . . . . . . . . 10
⊢ (((A
∈ On ∧ x ∈ On) ∧
(A +o x) = B) →
(B ∈ ω → x ∈ ω)) |
| 10 | 9 | exp31 293 |
. . . . . . . . 9
⊢ (A
∈ On → (x ∈ On →
((A +o x) = B →
(B ∈ ω → x ∈ ω)))) |
| 11 | 10 | com23 32 |
. . . . . . . 8
⊢ (A
∈ On → ((A +o
x) = B
→ (x ∈ On → (B ∈ ω → x ∈ ω)))) |
| 12 | 11 | com24 37 |
. . . . . . 7
⊢ (A
∈ On → (B ∈ ω →
(x ∈ On → ((A +o x) = B →
x ∈ ω)))) |
| 13 | 12 | imp4b 283 |
. . . . . 6
⊢ ((A
∈ On ∧ B ∈ ω) →
((x ∈ On ∧ (A +o x) = B) →
x ∈ ω)) |
| 14 | | pm3.27 260 |
. . . . . . 7
⊢ ((x
∈ On ∧ (A +o
x) = B)
→ (A +o x) = B) |
| 15 | 14 | a1i 7 |
. . . . . 6
⊢ ((A
∈ On ∧ B ∈ ω) →
((x ∈ On ∧ (A +o x) = B) →
(A +o x) = B)) |
| 16 | 13, 15 | jcad 455 |
. . . . 5
⊢ ((A
∈ On ∧ B ∈ ω) →
((x ∈ On ∧ (A +o x) = B) →
(x ∈ ω ∧ (A +o x) = B))) |
| 17 | | nnont 2379 |
. . . . . . 7
⊢ (x
∈ ω → x ∈
On) |
| 18 | 17 | anim1i 269 |
. . . . . 6
⊢ ((x
∈ ω ∧ (A
+o x) = B) → (x
∈ On ∧ (A +o
x) = B)) |
| 19 | 18 | a1i 7 |
. . . . 5
⊢ ((A
∈ On ∧ B ∈ ω) →
((x ∈ ω ∧ (A +o x) = B) →
(x ∈ On ∧ (A +o x) = B))) |
| 20 | 16, 19 | impbid 397 |
. . . 4
⊢ ((A
∈ On ∧ B ∈ ω) →
((x ∈ On ∧ (A +o x) = B) ↔
(x ∈ ω ∧ (A +o x) = B))) |
| 21 | 20 | birexdv2 1222 |
. . 3
⊢ ((A
∈ On ∧ B ∈ ω) →
(∃x ∈ On (A +o x) = B ↔
∃x ∈ ω (A +o x) = B)) |
| 22 | 3, 21 | bitrd 406 |
. 2
⊢ ((A
∈ On ∧ B ∈ ω) →
(A ⊆ B ↔ ∃x ∈ ω (A +o x) = B)) |
| 23 | | nnont 2379 |
. 2
⊢ (A
∈ ω → A ∈
On) |
| 24 | 22, 23 | sylan 343 |
1
⊢ ((A
∈ ω ∧ B ∈ ω)
→ (A ⊆ B ↔ ∃x ∈ ω (A +o x) = B)) |