Proof of Theorem sumsplitdc
| Step | Hyp | Ref
 | Expression | 
| 1 |   | sumsplit.4 | 
. . 3
⊢ (𝜑 → (𝐴 ∪ 𝐵) ⊆ 𝑍) | 
| 2 |   | sumsplitdc.a | 
. . . . 5
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → DECID 𝑘 ∈ 𝐴) | 
| 3 |   | sumsplitdc.b | 
. . . . 5
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → DECID 𝑘 ∈ 𝐵) | 
| 4 | 2, 3 | dcun 3560 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → DECID 𝑘 ∈ (𝐴 ∪ 𝐵)) | 
| 5 | 4 | ralrimiva 2570 | 
. . 3
⊢ (𝜑 → ∀𝑘 ∈ 𝑍 DECID 𝑘 ∈ (𝐴 ∪ 𝐵)) | 
| 6 |   | sumsplit.7 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ (𝐴 ∪ 𝐵)) → 𝐶 ∈ ℂ) | 
| 7 | 6 | ralrimiva 2570 | 
. . 3
⊢ (𝜑 → ∀𝑘 ∈ (𝐴 ∪ 𝐵)𝐶 ∈ ℂ) | 
| 8 |   | sumsplit.2 | 
. . . . 5
⊢ (𝜑 → 𝑀 ∈ ℤ) | 
| 9 |   | sumsplit.1 | 
. . . . . . 7
⊢ 𝑍 =
(ℤ≥‘𝑀) | 
| 10 | 9 | eqimssi 3239 | 
. . . . . 6
⊢ 𝑍 ⊆
(ℤ≥‘𝑀) | 
| 11 | 10 | a1i 9 | 
. . . . 5
⊢ (𝜑 → 𝑍 ⊆ (ℤ≥‘𝑀)) | 
| 12 | 9 | eleq2i 2263 | 
. . . . . . . . . 10
⊢ (𝑘 ∈ 𝑍 ↔ 𝑘 ∈ (ℤ≥‘𝑀)) | 
| 13 | 12 | biimpri 133 | 
. . . . . . . . 9
⊢ (𝑘 ∈
(ℤ≥‘𝑀) → 𝑘 ∈ 𝑍) | 
| 14 | 13 | orcd 734 | 
. . . . . . . 8
⊢ (𝑘 ∈
(ℤ≥‘𝑀) → (𝑘 ∈ 𝑍 ∨ ¬ 𝑘 ∈ 𝑍)) | 
| 15 |   | df-dc 836 | 
. . . . . . . 8
⊢
(DECID 𝑘 ∈ 𝑍 ↔ (𝑘 ∈ 𝑍 ∨ ¬ 𝑘 ∈ 𝑍)) | 
| 16 | 14, 15 | sylibr 134 | 
. . . . . . 7
⊢ (𝑘 ∈
(ℤ≥‘𝑀) → DECID 𝑘 ∈ 𝑍) | 
| 17 | 16 | adantl 277 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑘 ∈ (ℤ≥‘𝑀)) → DECID
𝑘 ∈ 𝑍) | 
| 18 | 17 | ralrimiva 2570 | 
. . . . 5
⊢ (𝜑 → ∀𝑘 ∈ (ℤ≥‘𝑀)DECID 𝑘 ∈ 𝑍) | 
| 19 | 8, 11, 18 | 3jca 1179 | 
. . . 4
⊢ (𝜑 → (𝑀 ∈ ℤ ∧ 𝑍 ⊆ (ℤ≥‘𝑀) ∧ ∀𝑘 ∈
(ℤ≥‘𝑀)DECID 𝑘 ∈ 𝑍)) | 
| 20 | 19 | orcd 734 | 
. . 3
⊢ (𝜑 → ((𝑀 ∈ ℤ ∧ 𝑍 ⊆ (ℤ≥‘𝑀) ∧ ∀𝑘 ∈
(ℤ≥‘𝑀)DECID 𝑘 ∈ 𝑍) ∨ 𝑍 ∈ Fin)) | 
| 21 | 1, 5, 7, 20 | isumss2 11558 | 
. 2
⊢ (𝜑 → Σ𝑘 ∈ (𝐴 ∪ 𝐵)𝐶 = Σ𝑘 ∈ 𝑍 if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0)) | 
| 22 |   | sumsplit.5 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → (𝐹‘𝑘) = if(𝑘 ∈ 𝐴, 𝐶, 0)) | 
| 23 |   | elun1 3330 | 
. . . . . . 7
⊢ (𝑘 ∈ 𝐴 → 𝑘 ∈ (𝐴 ∪ 𝐵)) | 
| 24 | 23, 6 | sylan2 286 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → 𝐶 ∈ ℂ) | 
| 25 | 24 | adantlr 477 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ 𝑘 ∈ 𝐴) → 𝐶 ∈ ℂ) | 
| 26 |   | 0cnd 8019 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐴) → 0 ∈ ℂ) | 
| 27 | 25, 26, 2 | ifcldadc 3590 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → if(𝑘 ∈ 𝐴, 𝐶, 0) ∈ ℂ) | 
| 28 |   | sumsplit.6 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → (𝐺‘𝑘) = if(𝑘 ∈ 𝐵, 𝐶, 0)) | 
| 29 |   | elun2 3331 | 
. . . . . . 7
⊢ (𝑘 ∈ 𝐵 → 𝑘 ∈ (𝐴 ∪ 𝐵)) | 
| 30 | 29, 6 | sylan2 286 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐵) → 𝐶 ∈ ℂ) | 
| 31 | 30 | adantlr 477 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ 𝑘 ∈ 𝐵) → 𝐶 ∈ ℂ) | 
| 32 |   | 0cnd 8019 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐵) → 0 ∈ ℂ) | 
| 33 | 31, 32, 3 | ifcldadc 3590 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → if(𝑘 ∈ 𝐵, 𝐶, 0) ∈ ℂ) | 
| 34 |   | sumsplit.8 | 
. . . 4
⊢ (𝜑 → seq𝑀( + , 𝐹) ∈ dom ⇝ ) | 
| 35 |   | sumsplit.9 | 
. . . 4
⊢ (𝜑 → seq𝑀( + , 𝐺) ∈ dom ⇝ ) | 
| 36 | 9, 8, 22, 27, 28, 33, 34, 35 | isumadd 11596 | 
. . 3
⊢ (𝜑 → Σ𝑘 ∈ 𝑍 (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0)) = (Σ𝑘 ∈ 𝑍 if(𝑘 ∈ 𝐴, 𝐶, 0) + Σ𝑘 ∈ 𝑍 if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 37 | 24 | addridd 8175 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → (𝐶 + 0) = 𝐶) | 
| 38 |   | iftrue 3566 | 
. . . . . . . . 9
⊢ (𝑘 ∈ 𝐴 → if(𝑘 ∈ 𝐴, 𝐶, 0) = 𝐶) | 
| 39 | 38 | adantl 277 | 
. . . . . . . 8
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → if(𝑘 ∈ 𝐴, 𝐶, 0) = 𝐶) | 
| 40 |   | noel 3454 | 
. . . . . . . . . . . 12
⊢  ¬
𝑘 ∈
∅ | 
| 41 |   | sumsplit.3 | 
. . . . . . . . . . . . . 14
⊢ (𝜑 → (𝐴 ∩ 𝐵) = ∅) | 
| 42 | 41 | eleq2d 2266 | 
. . . . . . . . . . . . 13
⊢ (𝜑 → (𝑘 ∈ (𝐴 ∩ 𝐵) ↔ 𝑘 ∈ ∅)) | 
| 43 |   | elin 3346 | 
. . . . . . . . . . . . 13
⊢ (𝑘 ∈ (𝐴 ∩ 𝐵) ↔ (𝑘 ∈ 𝐴 ∧ 𝑘 ∈ 𝐵)) | 
| 44 | 42, 43 | bitr3di 195 | 
. . . . . . . . . . . 12
⊢ (𝜑 → (𝑘 ∈ ∅ ↔ (𝑘 ∈ 𝐴 ∧ 𝑘 ∈ 𝐵))) | 
| 45 | 40, 44 | mtbii 675 | 
. . . . . . . . . . 11
⊢ (𝜑 → ¬ (𝑘 ∈ 𝐴 ∧ 𝑘 ∈ 𝐵)) | 
| 46 |   | imnan 691 | 
. . . . . . . . . . 11
⊢ ((𝑘 ∈ 𝐴 → ¬ 𝑘 ∈ 𝐵) ↔ ¬ (𝑘 ∈ 𝐴 ∧ 𝑘 ∈ 𝐵)) | 
| 47 | 45, 46 | sylibr 134 | 
. . . . . . . . . 10
⊢ (𝜑 → (𝑘 ∈ 𝐴 → ¬ 𝑘 ∈ 𝐵)) | 
| 48 | 47 | imp 124 | 
. . . . . . . . 9
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → ¬ 𝑘 ∈ 𝐵) | 
| 49 | 48 | iffalsed 3571 | 
. . . . . . . 8
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → if(𝑘 ∈ 𝐵, 𝐶, 0) = 0) | 
| 50 | 39, 49 | oveq12d 5940 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0)) = (𝐶 + 0)) | 
| 51 |   | iftrue 3566 | 
. . . . . . . . 9
⊢ (𝑘 ∈ (𝐴 ∪ 𝐵) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = 𝐶) | 
| 52 | 23, 51 | syl 14 | 
. . . . . . . 8
⊢ (𝑘 ∈ 𝐴 → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = 𝐶) | 
| 53 | 52 | adantl 277 | 
. . . . . . 7
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = 𝐶) | 
| 54 | 37, 50, 53 | 3eqtr4rd 2240 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 55 | 54 | adantlr 477 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ 𝑘 ∈ 𝐴) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 56 | 33 | adantr 276 | 
. . . . . . 7
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐴) → if(𝑘 ∈ 𝐵, 𝐶, 0) ∈ ℂ) | 
| 57 | 56 | addlidd 8176 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐴) → (0 + if(𝑘 ∈ 𝐵, 𝐶, 0)) = if(𝑘 ∈ 𝐵, 𝐶, 0)) | 
| 58 |   | iffalse 3569 | 
. . . . . . . . 9
⊢ (¬
𝑘 ∈ 𝐴 → if(𝑘 ∈ 𝐴, 𝐶, 0) = 0) | 
| 59 | 58 | adantl 277 | 
. . . . . . . 8
⊢ ((𝜑 ∧ ¬ 𝑘 ∈ 𝐴) → if(𝑘 ∈ 𝐴, 𝐶, 0) = 0) | 
| 60 | 59 | oveq1d 5937 | 
. . . . . . 7
⊢ ((𝜑 ∧ ¬ 𝑘 ∈ 𝐴) → (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0)) = (0 + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 61 | 60 | adantlr 477 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐴) → (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0)) = (0 + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 62 |   | elun 3304 | 
. . . . . . . . . 10
⊢ (𝑘 ∈ (𝐴 ∪ 𝐵) ↔ (𝑘 ∈ 𝐴 ∨ 𝑘 ∈ 𝐵)) | 
| 63 |   | biorf 745 | 
. . . . . . . . . 10
⊢ (¬
𝑘 ∈ 𝐴 → (𝑘 ∈ 𝐵 ↔ (𝑘 ∈ 𝐴 ∨ 𝑘 ∈ 𝐵))) | 
| 64 | 62, 63 | bitr4id 199 | 
. . . . . . . . 9
⊢ (¬
𝑘 ∈ 𝐴 → (𝑘 ∈ (𝐴 ∪ 𝐵) ↔ 𝑘 ∈ 𝐵)) | 
| 65 | 64 | adantl 277 | 
. . . . . . . 8
⊢ ((𝜑 ∧ ¬ 𝑘 ∈ 𝐴) → (𝑘 ∈ (𝐴 ∪ 𝐵) ↔ 𝑘 ∈ 𝐵)) | 
| 66 | 65 | ifbid 3582 | 
. . . . . . 7
⊢ ((𝜑 ∧ ¬ 𝑘 ∈ 𝐴) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = if(𝑘 ∈ 𝐵, 𝐶, 0)) | 
| 67 | 66 | adantlr 477 | 
. . . . . 6
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐴) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = if(𝑘 ∈ 𝐵, 𝐶, 0)) | 
| 68 | 57, 61, 67 | 3eqtr4rd 2240 | 
. . . . 5
⊢ (((𝜑 ∧ 𝑘 ∈ 𝑍) ∧ ¬ 𝑘 ∈ 𝐴) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 69 |   | exmiddc 837 | 
. . . . . 6
⊢
(DECID 𝑘 ∈ 𝐴 → (𝑘 ∈ 𝐴 ∨ ¬ 𝑘 ∈ 𝐴)) | 
| 70 | 2, 69 | syl 14 | 
. . . . 5
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → (𝑘 ∈ 𝐴 ∨ ¬ 𝑘 ∈ 𝐴)) | 
| 71 | 55, 68, 70 | mpjaodan 799 | 
. . . 4
⊢ ((𝜑 ∧ 𝑘 ∈ 𝑍) → if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 72 | 71 | sumeq2dv 11533 | 
. . 3
⊢ (𝜑 → Σ𝑘 ∈ 𝑍 if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0) = Σ𝑘 ∈ 𝑍 (if(𝑘 ∈ 𝐴, 𝐶, 0) + if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 73 | 1 | unssad 3340 | 
. . . . 5
⊢ (𝜑 → 𝐴 ⊆ 𝑍) | 
| 74 | 2 | ralrimiva 2570 | 
. . . . 5
⊢ (𝜑 → ∀𝑘 ∈ 𝑍 DECID 𝑘 ∈ 𝐴) | 
| 75 | 24 | ralrimiva 2570 | 
. . . . 5
⊢ (𝜑 → ∀𝑘 ∈ 𝐴 𝐶 ∈ ℂ) | 
| 76 | 73, 74, 75, 20 | isumss2 11558 | 
. . . 4
⊢ (𝜑 → Σ𝑘 ∈ 𝐴 𝐶 = Σ𝑘 ∈ 𝑍 if(𝑘 ∈ 𝐴, 𝐶, 0)) | 
| 77 | 1 | unssbd 3341 | 
. . . . 5
⊢ (𝜑 → 𝐵 ⊆ 𝑍) | 
| 78 | 3 | ralrimiva 2570 | 
. . . . 5
⊢ (𝜑 → ∀𝑘 ∈ 𝑍 DECID 𝑘 ∈ 𝐵) | 
| 79 | 30 | ralrimiva 2570 | 
. . . . 5
⊢ (𝜑 → ∀𝑘 ∈ 𝐵 𝐶 ∈ ℂ) | 
| 80 | 77, 78, 79, 20 | isumss2 11558 | 
. . . 4
⊢ (𝜑 → Σ𝑘 ∈ 𝐵 𝐶 = Σ𝑘 ∈ 𝑍 if(𝑘 ∈ 𝐵, 𝐶, 0)) | 
| 81 | 76, 80 | oveq12d 5940 | 
. . 3
⊢ (𝜑 → (Σ𝑘 ∈ 𝐴 𝐶 + Σ𝑘 ∈ 𝐵 𝐶) = (Σ𝑘 ∈ 𝑍 if(𝑘 ∈ 𝐴, 𝐶, 0) + Σ𝑘 ∈ 𝑍 if(𝑘 ∈ 𝐵, 𝐶, 0))) | 
| 82 | 36, 72, 81 | 3eqtr4rd 2240 | 
. 2
⊢ (𝜑 → (Σ𝑘 ∈ 𝐴 𝐶 + Σ𝑘 ∈ 𝐵 𝐶) = Σ𝑘 ∈ 𝑍 if(𝑘 ∈ (𝐴 ∪ 𝐵), 𝐶, 0)) | 
| 83 | 21, 82 | eqtr4d 2232 | 
1
⊢ (𝜑 → Σ𝑘 ∈ (𝐴 ∪ 𝐵)𝐶 = (Σ𝑘 ∈ 𝐴 𝐶 + Σ𝑘 ∈ 𝐵 𝐶)) |