Proof of Theorem axrep6
Step | Hyp | Ref
| Expression |
1 | | ax-rep 5209 |
. 2
⊢
(∀𝑤∃𝑦∀𝑧(∀𝑦𝜑 → 𝑧 = 𝑦) → ∃𝑦∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤(𝑤 ∈ 𝑥 ∧ ∀𝑦𝜑))) |
2 | | df-mo 2540 |
. . . 4
⊢
(∃*𝑧𝜑 ↔ ∃𝑦∀𝑧(𝜑 → 𝑧 = 𝑦)) |
3 | | 19.3v 1985 |
. . . . . . 7
⊢
(∀𝑦𝜑 ↔ 𝜑) |
4 | 3 | imbi1i 350 |
. . . . . 6
⊢
((∀𝑦𝜑 → 𝑧 = 𝑦) ↔ (𝜑 → 𝑧 = 𝑦)) |
5 | 4 | albii 1822 |
. . . . 5
⊢
(∀𝑧(∀𝑦𝜑 → 𝑧 = 𝑦) ↔ ∀𝑧(𝜑 → 𝑧 = 𝑦)) |
6 | 5 | exbii 1850 |
. . . 4
⊢
(∃𝑦∀𝑧(∀𝑦𝜑 → 𝑧 = 𝑦) ↔ ∃𝑦∀𝑧(𝜑 → 𝑧 = 𝑦)) |
7 | 2, 6 | bitr4i 277 |
. . 3
⊢
(∃*𝑧𝜑 ↔ ∃𝑦∀𝑧(∀𝑦𝜑 → 𝑧 = 𝑦)) |
8 | 7 | albii 1822 |
. 2
⊢
(∀𝑤∃*𝑧𝜑 ↔ ∀𝑤∃𝑦∀𝑧(∀𝑦𝜑 → 𝑧 = 𝑦)) |
9 | 3 | rexbii 3181 |
. . . . . 6
⊢
(∃𝑤 ∈
𝑥 ∀𝑦𝜑 ↔ ∃𝑤 ∈ 𝑥 𝜑) |
10 | | df-rex 3070 |
. . . . . 6
⊢
(∃𝑤 ∈
𝑥 ∀𝑦𝜑 ↔ ∃𝑤(𝑤 ∈ 𝑥 ∧ ∀𝑦𝜑)) |
11 | 9, 10 | bitr3i 276 |
. . . . 5
⊢
(∃𝑤 ∈
𝑥 𝜑 ↔ ∃𝑤(𝑤 ∈ 𝑥 ∧ ∀𝑦𝜑)) |
12 | 11 | bibi2i 338 |
. . . 4
⊢ ((𝑧 ∈ 𝑦 ↔ ∃𝑤 ∈ 𝑥 𝜑) ↔ (𝑧 ∈ 𝑦 ↔ ∃𝑤(𝑤 ∈ 𝑥 ∧ ∀𝑦𝜑))) |
13 | 12 | albii 1822 |
. . 3
⊢
(∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤 ∈ 𝑥 𝜑) ↔ ∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤(𝑤 ∈ 𝑥 ∧ ∀𝑦𝜑))) |
14 | 13 | exbii 1850 |
. 2
⊢
(∃𝑦∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤 ∈ 𝑥 𝜑) ↔ ∃𝑦∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤(𝑤 ∈ 𝑥 ∧ ∀𝑦𝜑))) |
15 | 1, 8, 14 | 3imtr4i 292 |
1
⊢
(∀𝑤∃*𝑧𝜑 → ∃𝑦∀𝑧(𝑧 ∈ 𝑦 ↔ ∃𝑤 ∈ 𝑥 𝜑)) |