| Step | Hyp | Ref
| Expression |
| 1 | | cbvralsv 2745 |
. 2
⊢
(∀𝑥 ∈
(𝐴 × 𝐵)𝜑 ↔ ∀𝑣 ∈ (𝐴 × 𝐵)[𝑣 / 𝑥]𝜑) |
| 2 | | cbvralsv 2745 |
. . . 4
⊢
(∀𝑧 ∈
𝐵 [𝑤 / 𝑦]𝜓 ↔ ∀𝑢 ∈ 𝐵 [𝑢 / 𝑧][𝑤 / 𝑦]𝜓) |
| 3 | 2 | ralbii 2503 |
. . 3
⊢
(∀𝑤 ∈
𝐴 ∀𝑧 ∈ 𝐵 [𝑤 / 𝑦]𝜓 ↔ ∀𝑤 ∈ 𝐴 ∀𝑢 ∈ 𝐵 [𝑢 / 𝑧][𝑤 / 𝑦]𝜓) |
| 4 | | nfv 1542 |
. . . 4
⊢
Ⅎ𝑤∀𝑧 ∈ 𝐵 𝜓 |
| 5 | | nfcv 2339 |
. . . . 5
⊢
Ⅎ𝑦𝐵 |
| 6 | | nfs1v 1958 |
. . . . 5
⊢
Ⅎ𝑦[𝑤 / 𝑦]𝜓 |
| 7 | 5, 6 | nfralxy 2535 |
. . . 4
⊢
Ⅎ𝑦∀𝑧 ∈ 𝐵 [𝑤 / 𝑦]𝜓 |
| 8 | | sbequ12 1785 |
. . . . 5
⊢ (𝑦 = 𝑤 → (𝜓 ↔ [𝑤 / 𝑦]𝜓)) |
| 9 | 8 | ralbidv 2497 |
. . . 4
⊢ (𝑦 = 𝑤 → (∀𝑧 ∈ 𝐵 𝜓 ↔ ∀𝑧 ∈ 𝐵 [𝑤 / 𝑦]𝜓)) |
| 10 | 4, 7, 9 | cbvral 2725 |
. . 3
⊢
(∀𝑦 ∈
𝐴 ∀𝑧 ∈ 𝐵 𝜓 ↔ ∀𝑤 ∈ 𝐴 ∀𝑧 ∈ 𝐵 [𝑤 / 𝑦]𝜓) |
| 11 | | vex 2766 |
. . . . . 6
⊢ 𝑤 ∈ V |
| 12 | | vex 2766 |
. . . . . 6
⊢ 𝑢 ∈ V |
| 13 | 11, 12 | eqvinop 4276 |
. . . . 5
⊢ (𝑣 = 〈𝑤, 𝑢〉 ↔ ∃𝑦∃𝑧(𝑣 = 〈𝑦, 𝑧〉 ∧ 〈𝑦, 𝑧〉 = 〈𝑤, 𝑢〉)) |
| 14 | | ralxpf.1 |
. . . . . . . 8
⊢
Ⅎ𝑦𝜑 |
| 15 | 14 | nfsb 1965 |
. . . . . . 7
⊢
Ⅎ𝑦[𝑣 / 𝑥]𝜑 |
| 16 | 6 | nfsb 1965 |
. . . . . . 7
⊢
Ⅎ𝑦[𝑢 / 𝑧][𝑤 / 𝑦]𝜓 |
| 17 | 15, 16 | nfbi 1603 |
. . . . . 6
⊢
Ⅎ𝑦([𝑣 / 𝑥]𝜑 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓) |
| 18 | | ralxpf.2 |
. . . . . . . . 9
⊢
Ⅎ𝑧𝜑 |
| 19 | 18 | nfsb 1965 |
. . . . . . . 8
⊢
Ⅎ𝑧[𝑣 / 𝑥]𝜑 |
| 20 | | nfs1v 1958 |
. . . . . . . 8
⊢
Ⅎ𝑧[𝑢 / 𝑧][𝑤 / 𝑦]𝜓 |
| 21 | 19, 20 | nfbi 1603 |
. . . . . . 7
⊢
Ⅎ𝑧([𝑣 / 𝑥]𝜑 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓) |
| 22 | | ralxpf.3 |
. . . . . . . . 9
⊢
Ⅎ𝑥𝜓 |
| 23 | | ralxpf.4 |
. . . . . . . . 9
⊢ (𝑥 = 〈𝑦, 𝑧〉 → (𝜑 ↔ 𝜓)) |
| 24 | 22, 23 | sbhypf 2813 |
. . . . . . . 8
⊢ (𝑣 = 〈𝑦, 𝑧〉 → ([𝑣 / 𝑥]𝜑 ↔ 𝜓)) |
| 25 | | vex 2766 |
. . . . . . . . . 10
⊢ 𝑦 ∈ V |
| 26 | | vex 2766 |
. . . . . . . . . 10
⊢ 𝑧 ∈ V |
| 27 | 25, 26 | opth 4270 |
. . . . . . . . 9
⊢
(〈𝑦, 𝑧〉 = 〈𝑤, 𝑢〉 ↔ (𝑦 = 𝑤 ∧ 𝑧 = 𝑢)) |
| 28 | | sbequ12 1785 |
. . . . . . . . . 10
⊢ (𝑧 = 𝑢 → ([𝑤 / 𝑦]𝜓 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 29 | 8, 28 | sylan9bb 462 |
. . . . . . . . 9
⊢ ((𝑦 = 𝑤 ∧ 𝑧 = 𝑢) → (𝜓 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 30 | 27, 29 | sylbi 121 |
. . . . . . . 8
⊢
(〈𝑦, 𝑧〉 = 〈𝑤, 𝑢〉 → (𝜓 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 31 | 24, 30 | sylan9bb 462 |
. . . . . . 7
⊢ ((𝑣 = 〈𝑦, 𝑧〉 ∧ 〈𝑦, 𝑧〉 = 〈𝑤, 𝑢〉) → ([𝑣 / 𝑥]𝜑 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 32 | 21, 31 | exlimi 1608 |
. . . . . 6
⊢
(∃𝑧(𝑣 = 〈𝑦, 𝑧〉 ∧ 〈𝑦, 𝑧〉 = 〈𝑤, 𝑢〉) → ([𝑣 / 𝑥]𝜑 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 33 | 17, 32 | exlimi 1608 |
. . . . 5
⊢
(∃𝑦∃𝑧(𝑣 = 〈𝑦, 𝑧〉 ∧ 〈𝑦, 𝑧〉 = 〈𝑤, 𝑢〉) → ([𝑣 / 𝑥]𝜑 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 34 | 13, 33 | sylbi 121 |
. . . 4
⊢ (𝑣 = 〈𝑤, 𝑢〉 → ([𝑣 / 𝑥]𝜑 ↔ [𝑢 / 𝑧][𝑤 / 𝑦]𝜓)) |
| 35 | 34 | ralxp 4809 |
. . 3
⊢
(∀𝑣 ∈
(𝐴 × 𝐵)[𝑣 / 𝑥]𝜑 ↔ ∀𝑤 ∈ 𝐴 ∀𝑢 ∈ 𝐵 [𝑢 / 𝑧][𝑤 / 𝑦]𝜓) |
| 36 | 3, 10, 35 | 3bitr4ri 213 |
. 2
⊢
(∀𝑣 ∈
(𝐴 × 𝐵)[𝑣 / 𝑥]𝜑 ↔ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 𝜓) |
| 37 | 1, 36 | bitri 184 |
1
⊢
(∀𝑥 ∈
(𝐴 × 𝐵)𝜑 ↔ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 𝜓) |