Proof of Theorem elrabsf
| Step | Hyp | Ref
| Expression |
| 1 | | elrabsf.1 |
. . . 4
⊢ (y
∈ B → ∀x y ∈
B) |
| 2 | | ax-17 925 |
. . . 4
⊢ (y
∈ B → ∀z y ∈
B) |
| 3 | | ax-17 925 |
. . . 4
⊢ (φ
→ ∀zφ) |
| 4 | | hbs1 986 |
. . . 4
⊢ ([z /
x]φ
→ ∀x[z / x]φ) |
| 5 | | sbequ12 865 |
. . . 4
⊢ (x =
z → (φ ↔ [z / x]φ)) |
| 6 | 1, 2, 3, 4, 5 | cbvrab 1425 |
. . 3
⊢ {x
∈ B∣φ} = {z
∈ B∣[z / x]φ} |
| 7 | 6 | eleq2i 1153 |
. 2
⊢ (A
∈ {x ∈ B∣φ}
↔ A ∈ {z ∈ B∣[z /
x]φ}) |
| 8 | | ax-17 925 |
. . . 4
⊢ (w
∈ A → ∀z w ∈
A) |
| 9 | | ax-17 925 |
. . . 4
⊢ (w
∈ B → ∀z w ∈
B) |
| 10 | 8 | hbsbc 1446 |
. . . 4
⊢ ((A
∈ V → [A / z][z / x]φ) →
∀z(A ∈ V → [A / z][z / x]φ)) |
| 11 | | sbceq1 1443 |
. . . . 5
⊢ (z =
A → ([z / x]φ ↔ [A / z][z / x]φ)) |
| 12 | | 19.8a 712 |
. . . . . . 7
⊢ (z =
A → ∃z z = A) |
| 13 | | isset 1351 |
. . . . . . 7
⊢ (A
∈ V ↔ ∃z z = A) |
| 14 | 12, 13 | sylibr 175 |
. . . . . 6
⊢ (z =
A → A ∈ V) |
| 15 | | biimt 549 |
. . . . . 6
⊢ (A
∈ V → ([A / z][z / x]φ ↔
(A ∈ V → [A / z][z / x]φ))) |
| 16 | 14, 15 | syl 12 |
. . . . 5
⊢ (z =
A → ([A / z][z / x]φ ↔ (A ∈ V → [A / z][z / x]φ))) |
| 17 | 11, 16 | bitrd 406 |
. . . 4
⊢ (z =
A → ([z / x]φ ↔ (A ∈ V → [A / z][z / x]φ))) |
| 18 | 8, 9, 10, 17 | elrabf 1421 |
. . 3
⊢ (A
∈ {z ∈ B∣[z /
x]φ} ↔ (A ∈ B ∧
(A ∈ V → [A / z][z / x]φ))) |
| 19 | | elisset 1354 |
. . . . 5
⊢ (A
∈ B → A ∈ V) |
| 20 | 19, 15 | syl 12 |
. . . 4
⊢ (A
∈ B → ([A / z][z / x]φ ↔ (A ∈ V → [A / z][z / x]φ))) |
| 21 | 20 | pm5.32i 489 |
. . 3
⊢ ((A
∈ B ∧ [A / z][z / x]φ) ↔ (A ∈ B ∧
(A ∈ V → [A / z][z / x]φ))) |
| 22 | 18, 21 | bitr4 154 |
. 2
⊢ (A
∈ {z ∈ B∣[z /
x]φ} ↔ (A ∈ B ∧
[A / z][z / x]φ)) |
| 23 | | sbcco 1448 |
. . 3
⊢ (A
∈ B → ([A / z][z / x]φ ↔ [A / x]φ)) |
| 24 | 23 | pm5.32i 489 |
. 2
⊢ ((A
∈ B ∧ [A / z][z / x]φ) ↔ (A ∈ B ∧
[A / x]φ)) |
| 25 | 7, 22, 24 | 3bitr 155 |
1
⊢ (A
∈ {x ∈ B∣φ}
↔ (A ∈ B ∧ [A /
x]φ)) |