| Step | Hyp | Ref
 | Expression | 
| 1 |   | csbeq1a 3093 | 
. . . 4
⊢ (𝑥 = 〈(2nd
‘𝑦), (1st
‘𝑦)〉 →
𝐵 =
⦋〈(2nd ‘𝑦), (1st ‘𝑦)〉 / 𝑥⦌𝐵) | 
| 2 |   | 2ndexg 6226 | 
. . . . . 6
⊢ (𝑦 ∈ V → (2nd
‘𝑦) ∈
V) | 
| 3 | 2 | elv 2767 | 
. . . . 5
⊢
(2nd ‘𝑦) ∈ V | 
| 4 |   | 1stexg 6225 | 
. . . . . 6
⊢ (𝑦 ∈ V → (1st
‘𝑦) ∈
V) | 
| 5 | 4 | elv 2767 | 
. . . . 5
⊢
(1st ‘𝑦) ∈ V | 
| 6 |   | vex 2766 | 
. . . . . . . 8
⊢ 𝑗 ∈ V | 
| 7 |   | vex 2766 | 
. . . . . . . 8
⊢ 𝑘 ∈ V | 
| 8 | 6, 7 | opex 4262 | 
. . . . . . 7
⊢
〈𝑗, 𝑘〉 ∈ V | 
| 9 |   | fsumcnv.1 | 
. . . . . . 7
⊢ (𝑥 = 〈𝑗, 𝑘〉 → 𝐵 = 𝐷) | 
| 10 | 8, 9 | csbie 3130 | 
. . . . . 6
⊢
⦋〈𝑗, 𝑘〉 / 𝑥⦌𝐵 = 𝐷 | 
| 11 |   | opeq12 3810 | 
. . . . . . 7
⊢ ((𝑗 = (2nd ‘𝑦) ∧ 𝑘 = (1st ‘𝑦)) → 〈𝑗, 𝑘〉 = 〈(2nd ‘𝑦), (1st ‘𝑦)〉) | 
| 12 | 11 | csbeq1d 3091 | 
. . . . . 6
⊢ ((𝑗 = (2nd ‘𝑦) ∧ 𝑘 = (1st ‘𝑦)) → ⦋〈𝑗, 𝑘〉 / 𝑥⦌𝐵 = ⦋〈(2nd
‘𝑦), (1st
‘𝑦)〉 / 𝑥⦌𝐵) | 
| 13 | 10, 12 | eqtr3id 2243 | 
. . . . 5
⊢ ((𝑗 = (2nd ‘𝑦) ∧ 𝑘 = (1st ‘𝑦)) → 𝐷 = ⦋〈(2nd
‘𝑦), (1st
‘𝑦)〉 / 𝑥⦌𝐵) | 
| 14 | 3, 5, 13 | csbie2 3134 | 
. . . 4
⊢
⦋(2nd ‘𝑦) / 𝑗⦌⦋(1st
‘𝑦) / 𝑘⦌𝐷 = ⦋〈(2nd
‘𝑦), (1st
‘𝑦)〉 / 𝑥⦌𝐵 | 
| 15 | 1, 14 | eqtr4di 2247 | 
. . 3
⊢ (𝑥 = 〈(2nd
‘𝑦), (1st
‘𝑦)〉 →
𝐵 =
⦋(2nd ‘𝑦) / 𝑗⦌⦋(1st
‘𝑦) / 𝑘⦌𝐷) | 
| 16 |   | fsumcnv.4 | 
. . . 4
⊢ (𝜑 → Rel 𝐴) | 
| 17 |   | fsumcnv.3 | 
. . . 4
⊢ (𝜑 → 𝐴 ∈ Fin) | 
| 18 |   | relcnvfi 7007 | 
. . . 4
⊢ ((Rel
𝐴 ∧ 𝐴 ∈ Fin) → ◡𝐴 ∈ Fin) | 
| 19 | 16, 17, 18 | syl2anc 411 | 
. . 3
⊢ (𝜑 → ◡𝐴 ∈ Fin) | 
| 20 |   | relcnv 5047 | 
. . . . 5
⊢ Rel ◡𝐴 | 
| 21 |   | cnvf1o 6283 | 
. . . . 5
⊢ (Rel
◡𝐴 → (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→◡◡𝐴) | 
| 22 | 20, 21 | ax-mp 5 | 
. . . 4
⊢ (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→◡◡𝐴 | 
| 23 |   | dfrel2 5120 | 
. . . . . 6
⊢ (Rel
𝐴 ↔ ◡◡𝐴 = 𝐴) | 
| 24 | 16, 23 | sylib 122 | 
. . . . 5
⊢ (𝜑 → ◡◡𝐴 = 𝐴) | 
| 25 |   | f1oeq3 5494 | 
. . . . 5
⊢ (◡◡𝐴 = 𝐴 → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→◡◡𝐴 ↔ (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→𝐴)) | 
| 26 | 24, 25 | syl 14 | 
. . . 4
⊢ (𝜑 → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→◡◡𝐴 ↔ (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→𝐴)) | 
| 27 | 22, 26 | mpbii 148 | 
. . 3
⊢ (𝜑 → (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}):◡𝐴–1-1-onto→𝐴) | 
| 28 |   | 1st2nd 6239 | 
. . . . . . 7
⊢ ((Rel
◡𝐴 ∧ 𝑦 ∈ ◡𝐴) → 𝑦 = 〈(1st ‘𝑦), (2nd ‘𝑦)〉) | 
| 29 | 20, 28 | mpan 424 | 
. . . . . 6
⊢ (𝑦 ∈ ◡𝐴 → 𝑦 = 〈(1st ‘𝑦), (2nd ‘𝑦)〉) | 
| 30 | 29 | fveq2d 5562 | 
. . . . 5
⊢ (𝑦 ∈ ◡𝐴 → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧})‘𝑦) = ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧})‘〈(1st ‘𝑦), (2nd ‘𝑦)〉)) | 
| 31 |   | id 19 | 
. . . . . . 7
⊢ (𝑦 ∈ ◡𝐴 → 𝑦 ∈ ◡𝐴) | 
| 32 | 29, 31 | eqeltrrd 2274 | 
. . . . . 6
⊢ (𝑦 ∈ ◡𝐴 → 〈(1st ‘𝑦), (2nd ‘𝑦)〉 ∈ ◡𝐴) | 
| 33 |   | sneq 3633 | 
. . . . . . . . . 10
⊢ (𝑧 = 〈(1st
‘𝑦), (2nd
‘𝑦)〉 →
{𝑧} =
{〈(1st ‘𝑦), (2nd ‘𝑦)〉}) | 
| 34 | 33 | cnveqd 4842 | 
. . . . . . . . 9
⊢ (𝑧 = 〈(1st
‘𝑦), (2nd
‘𝑦)〉 →
◡{𝑧} = ◡{〈(1st ‘𝑦), (2nd ‘𝑦)〉}) | 
| 35 | 34 | unieqd 3850 | 
. . . . . . . 8
⊢ (𝑧 = 〈(1st
‘𝑦), (2nd
‘𝑦)〉 →
∪ ◡{𝑧} = ∪
◡{〈(1st ‘𝑦), (2nd ‘𝑦)〉}) | 
| 36 |   | opswapg 5156 | 
. . . . . . . . 9
⊢
(((1st ‘𝑦) ∈ V ∧ (2nd ‘𝑦) ∈ V) → ∪ ◡{〈(1st ‘𝑦), (2nd ‘𝑦)〉} = 〈(2nd
‘𝑦), (1st
‘𝑦)〉) | 
| 37 | 5, 3, 36 | mp2an 426 | 
. . . . . . . 8
⊢ ∪ ◡{〈(1st ‘𝑦), (2nd ‘𝑦)〉} = 〈(2nd
‘𝑦), (1st
‘𝑦)〉 | 
| 38 | 35, 37 | eqtrdi 2245 | 
. . . . . . 7
⊢ (𝑧 = 〈(1st
‘𝑦), (2nd
‘𝑦)〉 →
∪ ◡{𝑧} = 〈(2nd
‘𝑦), (1st
‘𝑦)〉) | 
| 39 |   | eqid 2196 | 
. . . . . . 7
⊢ (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}) = (𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧}) | 
| 40 | 3, 5 | opex 4262 | 
. . . . . . 7
⊢
〈(2nd ‘𝑦), (1st ‘𝑦)〉 ∈ V | 
| 41 | 38, 39, 40 | fvmpt 5638 | 
. . . . . 6
⊢
(〈(1st ‘𝑦), (2nd ‘𝑦)〉 ∈ ◡𝐴 → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧})‘〈(1st ‘𝑦), (2nd ‘𝑦)〉) = 〈(2nd
‘𝑦), (1st
‘𝑦)〉) | 
| 42 | 32, 41 | syl 14 | 
. . . . 5
⊢ (𝑦 ∈ ◡𝐴 → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧})‘〈(1st ‘𝑦), (2nd ‘𝑦)〉) = 〈(2nd
‘𝑦), (1st
‘𝑦)〉) | 
| 43 | 30, 42 | eqtrd 2229 | 
. . . 4
⊢ (𝑦 ∈ ◡𝐴 → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧})‘𝑦) = 〈(2nd ‘𝑦), (1st ‘𝑦)〉) | 
| 44 | 43 | adantl 277 | 
. . 3
⊢ ((𝜑 ∧ 𝑦 ∈ ◡𝐴) → ((𝑧 ∈ ◡𝐴 ↦ ∪ ◡{𝑧})‘𝑦) = 〈(2nd ‘𝑦), (1st ‘𝑦)〉) | 
| 45 |   | fsumcnv.5 | 
. . 3
⊢ ((𝜑 ∧ 𝑥 ∈ 𝐴) → 𝐵 ∈ ℂ) | 
| 46 | 15, 19, 27, 44, 45 | fsumf1o 11555 | 
. 2
⊢ (𝜑 → Σ𝑥 ∈ 𝐴 𝐵 = Σ𝑦 ∈ ◡ 𝐴⦋(2nd ‘𝑦) / 𝑗⦌⦋(1st
‘𝑦) / 𝑘⦌𝐷) | 
| 47 |   | csbeq1a 3093 | 
. . . . 5
⊢ (𝑦 = 〈(1st
‘𝑦), (2nd
‘𝑦)〉 →
𝐶 =
⦋〈(1st ‘𝑦), (2nd ‘𝑦)〉 / 𝑦⦌𝐶) | 
| 48 | 29, 47 | syl 14 | 
. . . 4
⊢ (𝑦 ∈ ◡𝐴 → 𝐶 = ⦋〈(1st
‘𝑦), (2nd
‘𝑦)〉 / 𝑦⦌𝐶) | 
| 49 | 7, 6 | opex 4262 | 
. . . . . . 7
⊢
〈𝑘, 𝑗〉 ∈ V | 
| 50 |   | fsumcnv.2 | 
. . . . . . 7
⊢ (𝑦 = 〈𝑘, 𝑗〉 → 𝐶 = 𝐷) | 
| 51 | 49, 50 | csbie 3130 | 
. . . . . 6
⊢
⦋〈𝑘, 𝑗〉 / 𝑦⦌𝐶 = 𝐷 | 
| 52 |   | opeq12 3810 | 
. . . . . . . 8
⊢ ((𝑘 = (1st ‘𝑦) ∧ 𝑗 = (2nd ‘𝑦)) → 〈𝑘, 𝑗〉 = 〈(1st ‘𝑦), (2nd ‘𝑦)〉) | 
| 53 | 52 | ancoms 268 | 
. . . . . . 7
⊢ ((𝑗 = (2nd ‘𝑦) ∧ 𝑘 = (1st ‘𝑦)) → 〈𝑘, 𝑗〉 = 〈(1st ‘𝑦), (2nd ‘𝑦)〉) | 
| 54 | 53 | csbeq1d 3091 | 
. . . . . 6
⊢ ((𝑗 = (2nd ‘𝑦) ∧ 𝑘 = (1st ‘𝑦)) → ⦋〈𝑘, 𝑗〉 / 𝑦⦌𝐶 = ⦋〈(1st
‘𝑦), (2nd
‘𝑦)〉 / 𝑦⦌𝐶) | 
| 55 | 51, 54 | eqtr3id 2243 | 
. . . . 5
⊢ ((𝑗 = (2nd ‘𝑦) ∧ 𝑘 = (1st ‘𝑦)) → 𝐷 = ⦋〈(1st
‘𝑦), (2nd
‘𝑦)〉 / 𝑦⦌𝐶) | 
| 56 | 3, 5, 55 | csbie2 3134 | 
. . . 4
⊢
⦋(2nd ‘𝑦) / 𝑗⦌⦋(1st
‘𝑦) / 𝑘⦌𝐷 = ⦋〈(1st
‘𝑦), (2nd
‘𝑦)〉 / 𝑦⦌𝐶 | 
| 57 | 48, 56 | eqtr4di 2247 | 
. . 3
⊢ (𝑦 ∈ ◡𝐴 → 𝐶 = ⦋(2nd
‘𝑦) / 𝑗⦌⦋(1st
‘𝑦) / 𝑘⦌𝐷) | 
| 58 | 57 | sumeq2i 11529 | 
. 2
⊢
Σ𝑦 ∈
◡ 𝐴𝐶 = Σ𝑦 ∈ ◡ 𝐴⦋(2nd ‘𝑦) / 𝑗⦌⦋(1st
‘𝑦) / 𝑘⦌𝐷 | 
| 59 | 46, 58 | eqtr4di 2247 | 
1
⊢ (𝜑 → Σ𝑥 ∈ 𝐴 𝐵 = Σ𝑦 ∈ ◡ 𝐴𝐶) |