| Step | Hyp | Ref
 | Expression | 
| 1 |   | vex 2766 | 
. . . . . . . 8
⊢ 𝑧 ∈ V | 
| 2 |   | vex 2766 | 
. . . . . . . 8
⊢ 𝑤 ∈ V | 
| 3 | 1, 2 | op1std 6206 | 
. . . . . . 7
⊢ (𝑣 = 〈𝑧, 𝑤〉 → (1st ‘𝑣) = 𝑧) | 
| 4 | 3 | csbeq1d 3091 | 
. . . . . 6
⊢ (𝑣 = 〈𝑧, 𝑤〉 → ⦋(1st
‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶 = ⦋𝑧 / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶) | 
| 5 | 1, 2 | op2ndd 6207 | 
. . . . . . . 8
⊢ (𝑣 = 〈𝑧, 𝑤〉 → (2nd ‘𝑣) = 𝑤) | 
| 6 | 5 | csbeq1d 3091 | 
. . . . . . 7
⊢ (𝑣 = 〈𝑧, 𝑤〉 → ⦋(2nd
‘𝑣) / 𝑦⦌𝐶 = ⦋𝑤 / 𝑦⦌𝐶) | 
| 7 | 6 | csbeq2dv 3110 | 
. . . . . 6
⊢ (𝑣 = 〈𝑧, 𝑤〉 → ⦋𝑧 / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 8 | 4, 7 | eqtrd 2229 | 
. . . . 5
⊢ (𝑣 = 〈𝑧, 𝑤〉 → ⦋(1st
‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 9 | 8 | eleq1d 2265 | 
. . . 4
⊢ (𝑣 = 〈𝑧, 𝑤〉 → (⦋(1st
‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶 ∈ 𝐷 ↔ ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷)) | 
| 10 | 9 | raliunxp 4807 | 
. . 3
⊢
(∀𝑣 ∈
∪ 𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵)⦋(1st ‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶 ∈ 𝐷 ↔ ∀𝑧 ∈ 𝐴 ∀𝑤 ∈ ⦋ 𝑧 / 𝑥⦌𝐵⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷) | 
| 11 |   | nfv 1542 | 
. . . . . . 7
⊢
Ⅎ𝑧((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑣 = 𝐶) | 
| 12 |   | nfv 1542 | 
. . . . . . 7
⊢
Ⅎ𝑤((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑣 = 𝐶) | 
| 13 |   | nfv 1542 | 
. . . . . . . . 9
⊢
Ⅎ𝑥 𝑧 ∈ 𝐴 | 
| 14 |   | nfcsb1v 3117 | 
. . . . . . . . . 10
⊢
Ⅎ𝑥⦋𝑧 / 𝑥⦌𝐵 | 
| 15 | 14 | nfcri 2333 | 
. . . . . . . . 9
⊢
Ⅎ𝑥 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵 | 
| 16 | 13, 15 | nfan 1579 | 
. . . . . . . 8
⊢
Ⅎ𝑥(𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) | 
| 17 |   | nfcsb1v 3117 | 
. . . . . . . . 9
⊢
Ⅎ𝑥⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 | 
| 18 | 17 | nfeq2 2351 | 
. . . . . . . 8
⊢
Ⅎ𝑥 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 | 
| 19 | 16, 18 | nfan 1579 | 
. . . . . . 7
⊢
Ⅎ𝑥((𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) ∧ 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 20 |   | nfv 1542 | 
. . . . . . . 8
⊢
Ⅎ𝑦(𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) | 
| 21 |   | nfcv 2339 | 
. . . . . . . . . 10
⊢
Ⅎ𝑦𝑧 | 
| 22 |   | nfcsb1v 3117 | 
. . . . . . . . . 10
⊢
Ⅎ𝑦⦋𝑤 / 𝑦⦌𝐶 | 
| 23 | 21, 22 | nfcsb 3122 | 
. . . . . . . . 9
⊢
Ⅎ𝑦⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 | 
| 24 | 23 | nfeq2 2351 | 
. . . . . . . 8
⊢
Ⅎ𝑦 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 | 
| 25 | 20, 24 | nfan 1579 | 
. . . . . . 7
⊢
Ⅎ𝑦((𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) ∧ 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 26 |   | eleq1 2259 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑧 → (𝑥 ∈ 𝐴 ↔ 𝑧 ∈ 𝐴)) | 
| 27 | 26 | adantr 276 | 
. . . . . . . . 9
⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → (𝑥 ∈ 𝐴 ↔ 𝑧 ∈ 𝐴)) | 
| 28 |   | eleq1 2259 | 
. . . . . . . . . 10
⊢ (𝑦 = 𝑤 → (𝑦 ∈ 𝐵 ↔ 𝑤 ∈ 𝐵)) | 
| 29 |   | csbeq1a 3093 | 
. . . . . . . . . . 11
⊢ (𝑥 = 𝑧 → 𝐵 = ⦋𝑧 / 𝑥⦌𝐵) | 
| 30 | 29 | eleq2d 2266 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑧 → (𝑤 ∈ 𝐵 ↔ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵)) | 
| 31 | 28, 30 | sylan9bbr 463 | 
. . . . . . . . 9
⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → (𝑦 ∈ 𝐵 ↔ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵)) | 
| 32 | 27, 31 | anbi12d 473 | 
. . . . . . . 8
⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ↔ (𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵))) | 
| 33 |   | csbeq1a 3093 | 
. . . . . . . . . 10
⊢ (𝑦 = 𝑤 → 𝐶 = ⦋𝑤 / 𝑦⦌𝐶) | 
| 34 |   | csbeq1a 3093 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑧 → ⦋𝑤 / 𝑦⦌𝐶 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 35 | 33, 34 | sylan9eqr 2251 | 
. . . . . . . . 9
⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → 𝐶 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 36 | 35 | eqeq2d 2208 | 
. . . . . . . 8
⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → (𝑣 = 𝐶 ↔ 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶)) | 
| 37 | 32, 36 | anbi12d 473 | 
. . . . . . 7
⊢ ((𝑥 = 𝑧 ∧ 𝑦 = 𝑤) → (((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑣 = 𝐶) ↔ ((𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) ∧ 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶))) | 
| 38 | 11, 12, 19, 25, 37 | cbvoprab12 5996 | 
. . . . . 6
⊢
{〈〈𝑥,
𝑦〉, 𝑣〉 ∣ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑣 = 𝐶)} = {〈〈𝑧, 𝑤〉, 𝑣〉 ∣ ((𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) ∧ 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶)} | 
| 39 |   | df-mpo 5927 | 
. . . . . 6
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) = {〈〈𝑥, 𝑦〉, 𝑣〉 ∣ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝑣 = 𝐶)} | 
| 40 |   | df-mpo 5927 | 
. . . . . 6
⊢ (𝑧 ∈ 𝐴, 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵 ↦ ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) = {〈〈𝑧, 𝑤〉, 𝑣〉 ∣ ((𝑧 ∈ 𝐴 ∧ 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵) ∧ 𝑣 = ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶)} | 
| 41 | 38, 39, 40 | 3eqtr4i 2227 | 
. . . . 5
⊢ (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) = (𝑧 ∈ 𝐴, 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵 ↦ ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 42 |   | fmpox.1 | 
. . . . 5
⊢ 𝐹 = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) | 
| 43 | 8 | mpomptx 6013 | 
. . . . 5
⊢ (𝑣 ∈ ∪ 𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵) ↦ ⦋(1st
‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶) = (𝑧 ∈ 𝐴, 𝑤 ∈ ⦋𝑧 / 𝑥⦌𝐵 ↦ ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶) | 
| 44 | 41, 42, 43 | 3eqtr4i 2227 | 
. . . 4
⊢ 𝐹 = (𝑣 ∈ ∪
𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵) ↦ ⦋(1st
‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶) | 
| 45 | 44 | fmpt 5712 | 
. . 3
⊢
(∀𝑣 ∈
∪ 𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵)⦋(1st ‘𝑣) / 𝑥⦌⦋(2nd
‘𝑣) / 𝑦⦌𝐶 ∈ 𝐷 ↔ 𝐹:∪ 𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵)⟶𝐷) | 
| 46 | 10, 45 | bitr3i 186 | 
. 2
⊢
(∀𝑧 ∈
𝐴 ∀𝑤 ∈ ⦋ 𝑧 / 𝑥⦌𝐵⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷 ↔ 𝐹:∪ 𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵)⟶𝐷) | 
| 47 |   | nfv 1542 | 
. . 3
⊢
Ⅎ𝑧∀𝑦 ∈ 𝐵 𝐶 ∈ 𝐷 | 
| 48 | 17 | nfel1 2350 | 
. . . 4
⊢
Ⅎ𝑥⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷 | 
| 49 | 14, 48 | nfralxy 2535 | 
. . 3
⊢
Ⅎ𝑥∀𝑤 ∈ ⦋ 𝑧 / 𝑥⦌𝐵⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷 | 
| 50 |   | nfv 1542 | 
. . . . 5
⊢
Ⅎ𝑤 𝐶 ∈ 𝐷 | 
| 51 | 22 | nfel1 2350 | 
. . . . 5
⊢
Ⅎ𝑦⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷 | 
| 52 | 33 | eleq1d 2265 | 
. . . . 5
⊢ (𝑦 = 𝑤 → (𝐶 ∈ 𝐷 ↔ ⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷)) | 
| 53 | 50, 51, 52 | cbvral 2725 | 
. . . 4
⊢
(∀𝑦 ∈
𝐵 𝐶 ∈ 𝐷 ↔ ∀𝑤 ∈ 𝐵 ⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷) | 
| 54 | 34 | eleq1d 2265 | 
. . . . 5
⊢ (𝑥 = 𝑧 → (⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷 ↔ ⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷)) | 
| 55 | 29, 54 | raleqbidv 2709 | 
. . . 4
⊢ (𝑥 = 𝑧 → (∀𝑤 ∈ 𝐵 ⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷 ↔ ∀𝑤 ∈ ⦋ 𝑧 / 𝑥⦌𝐵⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷)) | 
| 56 | 53, 55 | bitrid 192 | 
. . 3
⊢ (𝑥 = 𝑧 → (∀𝑦 ∈ 𝐵 𝐶 ∈ 𝐷 ↔ ∀𝑤 ∈ ⦋ 𝑧 / 𝑥⦌𝐵⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷)) | 
| 57 | 47, 49, 56 | cbvral 2725 | 
. 2
⊢
(∀𝑥 ∈
𝐴 ∀𝑦 ∈ 𝐵 𝐶 ∈ 𝐷 ↔ ∀𝑧 ∈ 𝐴 ∀𝑤 ∈ ⦋ 𝑧 / 𝑥⦌𝐵⦋𝑧 / 𝑥⦌⦋𝑤 / 𝑦⦌𝐶 ∈ 𝐷) | 
| 58 |   | nfcv 2339 | 
. . . 4
⊢
Ⅎ𝑧({𝑥} × 𝐵) | 
| 59 |   | nfcv 2339 | 
. . . . 5
⊢
Ⅎ𝑥{𝑧} | 
| 60 | 59, 14 | nfxp 4690 | 
. . . 4
⊢
Ⅎ𝑥({𝑧} × ⦋𝑧 / 𝑥⦌𝐵) | 
| 61 |   | sneq 3633 | 
. . . . 5
⊢ (𝑥 = 𝑧 → {𝑥} = {𝑧}) | 
| 62 | 61, 29 | xpeq12d 4688 | 
. . . 4
⊢ (𝑥 = 𝑧 → ({𝑥} × 𝐵) = ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵)) | 
| 63 | 58, 60, 62 | cbviun 3953 | 
. . 3
⊢ ∪ 𝑥 ∈ 𝐴 ({𝑥} × 𝐵) = ∪
𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵) | 
| 64 | 63 | feq2i 5401 | 
. 2
⊢ (𝐹:∪ 𝑥 ∈ 𝐴 ({𝑥} × 𝐵)⟶𝐷 ↔ 𝐹:∪ 𝑧 ∈ 𝐴 ({𝑧} × ⦋𝑧 / 𝑥⦌𝐵)⟶𝐷) | 
| 65 | 46, 57, 64 | 3bitr4i 212 | 
1
⊢
(∀𝑥 ∈
𝐴 ∀𝑦 ∈ 𝐵 𝐶 ∈ 𝐷 ↔ 𝐹:∪ 𝑥 ∈ 𝐴 ({𝑥} × 𝐵)⟶𝐷) |