| Step | Hyp | Ref
 | Expression | 
| 1 |   | rngop.1 | 
. . . . 5
⊢ 𝐹 = (𝑥 ∈ 𝐴, 𝑦 ∈ 𝐵 ↦ 𝐶) | 
| 2 | 1 | rnmpo 6033 | 
. . . 4
⊢ ran 𝐹 = {𝑤 ∣ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑤 = 𝐶} | 
| 3 | 2 | rexeqi 2698 | 
. . 3
⊢
(∃𝑧 ∈ ran
𝐹𝜑 ↔ ∃𝑧 ∈ {𝑤 ∣ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑤 = 𝐶}𝜑) | 
| 4 |   | eqeq1 2203 | 
. . . . 5
⊢ (𝑤 = 𝑧 → (𝑤 = 𝐶 ↔ 𝑧 = 𝐶)) | 
| 5 | 4 | 2rexbidv 2522 | 
. . . 4
⊢ (𝑤 = 𝑧 → (∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑤 = 𝐶 ↔ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = 𝐶)) | 
| 6 | 5 | rexab 2926 | 
. . 3
⊢
(∃𝑧 ∈
{𝑤 ∣ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑤 = 𝐶}𝜑 ↔ ∃𝑧(∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 7 |   | rexcom4 2786 | 
. . . 4
⊢
(∃𝑥 ∈
𝐴 ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑧∃𝑥 ∈ 𝐴 (∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 8 |   | r19.41v 2653 | 
. . . . 5
⊢
(∃𝑥 ∈
𝐴 (∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ (∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 9 | 8 | exbii 1619 | 
. . . 4
⊢
(∃𝑧∃𝑥 ∈ 𝐴 (∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑧(∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 10 | 7, 9 | bitr2i 185 | 
. . 3
⊢
(∃𝑧(∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑥 ∈ 𝐴 ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 11 | 3, 6, 10 | 3bitri 206 | 
. 2
⊢
(∃𝑧 ∈ ran
𝐹𝜑 ↔ ∃𝑥 ∈ 𝐴 ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 12 |   | rexcom4 2786 | 
. . . . . 6
⊢
(∃𝑦 ∈
𝐵 ∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑧∃𝑦 ∈ 𝐵 (𝑧 = 𝐶 ∧ 𝜑)) | 
| 13 |   | r19.41v 2653 | 
. . . . . . 7
⊢
(∃𝑦 ∈
𝐵 (𝑧 = 𝐶 ∧ 𝜑) ↔ (∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 14 | 13 | exbii 1619 | 
. . . . . 6
⊢
(∃𝑧∃𝑦 ∈ 𝐵 (𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 15 | 12, 14 | bitri 184 | 
. . . . 5
⊢
(∃𝑦 ∈
𝐵 ∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑)) | 
| 16 |   | ralrnmpo.2 | 
. . . . . . . 8
⊢ (𝑧 = 𝐶 → (𝜑 ↔ 𝜓)) | 
| 17 | 16 | ceqsexgv 2893 | 
. . . . . . 7
⊢ (𝐶 ∈ 𝑉 → (∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ 𝜓)) | 
| 18 | 17 | ralimi 2560 | 
. . . . . 6
⊢
(∀𝑦 ∈
𝐵 𝐶 ∈ 𝑉 → ∀𝑦 ∈ 𝐵 (∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ 𝜓)) | 
| 19 |   | rexbi 2630 | 
. . . . . 6
⊢
(∀𝑦 ∈
𝐵 (∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ 𝜓) → (∃𝑦 ∈ 𝐵 ∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑦 ∈ 𝐵 𝜓)) | 
| 20 | 18, 19 | syl 14 | 
. . . . 5
⊢
(∀𝑦 ∈
𝐵 𝐶 ∈ 𝑉 → (∃𝑦 ∈ 𝐵 ∃𝑧(𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑦 ∈ 𝐵 𝜓)) | 
| 21 | 15, 20 | bitr3id 194 | 
. . . 4
⊢
(∀𝑦 ∈
𝐵 𝐶 ∈ 𝑉 → (∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑦 ∈ 𝐵 𝜓)) | 
| 22 | 21 | ralimi 2560 | 
. . 3
⊢
(∀𝑥 ∈
𝐴 ∀𝑦 ∈ 𝐵 𝐶 ∈ 𝑉 → ∀𝑥 ∈ 𝐴 (∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑦 ∈ 𝐵 𝜓)) | 
| 23 |   | rexbi 2630 | 
. . 3
⊢
(∀𝑥 ∈
𝐴 (∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑦 ∈ 𝐵 𝜓) → (∃𝑥 ∈ 𝐴 ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜓)) | 
| 24 | 22, 23 | syl 14 | 
. 2
⊢
(∀𝑥 ∈
𝐴 ∀𝑦 ∈ 𝐵 𝐶 ∈ 𝑉 → (∃𝑥 ∈ 𝐴 ∃𝑧(∃𝑦 ∈ 𝐵 𝑧 = 𝐶 ∧ 𝜑) ↔ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜓)) | 
| 25 | 11, 24 | bitrid 192 | 
1
⊢
(∀𝑥 ∈
𝐴 ∀𝑦 ∈ 𝐵 𝐶 ∈ 𝑉 → (∃𝑧 ∈ ran 𝐹𝜑 ↔ ∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜓)) |