| Step | Hyp | Ref
 | Expression | 
| 1 |   | r19.26 2623 | 
. . . 4
⊢
(∀𝑘 ∈
(ℤ≥‘𝑗)(𝜑 ∧ 𝜓) ↔ (∀𝑘 ∈ (ℤ≥‘𝑗)𝜑 ∧ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) | 
| 2 | 1 | rexbii 2504 | 
. . 3
⊢
(∃𝑗 ∈
ℤ ∀𝑘 ∈
(ℤ≥‘𝑗)(𝜑 ∧ 𝜓) ↔ ∃𝑗 ∈ ℤ (∀𝑘 ∈ (ℤ≥‘𝑗)𝜑 ∧ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) | 
| 3 |   | r19.40 2651 | 
. . 3
⊢
(∃𝑗 ∈
ℤ (∀𝑘 ∈
(ℤ≥‘𝑗)𝜑 ∧ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓) → (∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜑 ∧ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) | 
| 4 | 2, 3 | sylbi 121 | 
. 2
⊢
(∃𝑗 ∈
ℤ ∀𝑘 ∈
(ℤ≥‘𝑗)(𝜑 ∧ 𝜓) → (∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜑 ∧ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) | 
| 5 |   | uzf 9604 | 
. . . 4
⊢
ℤ≥:ℤ⟶𝒫 ℤ | 
| 6 |   | ffn 5407 | 
. . . 4
⊢
(ℤ≥:ℤ⟶𝒫 ℤ →
ℤ≥ Fn ℤ) | 
| 7 |   | raleq 2693 | 
. . . . 5
⊢ (𝑥 =
(ℤ≥‘𝑗) → (∀𝑘 ∈ 𝑥 𝜑 ↔ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜑)) | 
| 8 | 7 | rexrn 5699 | 
. . . 4
⊢
(ℤ≥ Fn ℤ → (∃𝑥 ∈ ran
ℤ≥∀𝑘 ∈ 𝑥 𝜑 ↔ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜑)) | 
| 9 | 5, 6, 8 | mp2b 8 | 
. . 3
⊢
(∃𝑥 ∈ ran
ℤ≥∀𝑘 ∈ 𝑥 𝜑 ↔ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜑) | 
| 10 |   | raleq 2693 | 
. . . . 5
⊢ (𝑦 =
(ℤ≥‘𝑗) → (∀𝑘 ∈ 𝑦 𝜓 ↔ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) | 
| 11 | 10 | rexrn 5699 | 
. . . 4
⊢
(ℤ≥ Fn ℤ → (∃𝑦 ∈ ran
ℤ≥∀𝑘 ∈ 𝑦 𝜓 ↔ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) | 
| 12 | 5, 6, 11 | mp2b 8 | 
. . 3
⊢
(∃𝑦 ∈ ran
ℤ≥∀𝑘 ∈ 𝑦 𝜓 ↔ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓) | 
| 13 |   | uzin2 11152 | 
. . . . . . . . 9
⊢ ((𝑥 ∈ ran
ℤ≥ ∧ 𝑦 ∈ ran ℤ≥) →
(𝑥 ∩ 𝑦) ∈ ran
ℤ≥) | 
| 14 |   | inss1 3383 | 
. . . . . . . . . . . 12
⊢ (𝑥 ∩ 𝑦) ⊆ 𝑥 | 
| 15 |   | ssralv 3247 | 
. . . . . . . . . . . 12
⊢ ((𝑥 ∩ 𝑦) ⊆ 𝑥 → (∀𝑘 ∈ 𝑥 𝜑 → ∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜑)) | 
| 16 | 14, 15 | ax-mp 5 | 
. . . . . . . . . . 11
⊢
(∀𝑘 ∈
𝑥 𝜑 → ∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜑) | 
| 17 |   | inss2 3384 | 
. . . . . . . . . . . 12
⊢ (𝑥 ∩ 𝑦) ⊆ 𝑦 | 
| 18 |   | ssralv 3247 | 
. . . . . . . . . . . 12
⊢ ((𝑥 ∩ 𝑦) ⊆ 𝑦 → (∀𝑘 ∈ 𝑦 𝜓 → ∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜓)) | 
| 19 | 17, 18 | ax-mp 5 | 
. . . . . . . . . . 11
⊢
(∀𝑘 ∈
𝑦 𝜓 → ∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜓) | 
| 20 | 16, 19 | anim12i 338 | 
. . . . . . . . . 10
⊢
((∀𝑘 ∈
𝑥 𝜑 ∧ ∀𝑘 ∈ 𝑦 𝜓) → (∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜑 ∧ ∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜓)) | 
| 21 |   | r19.26 2623 | 
. . . . . . . . . 10
⊢
(∀𝑘 ∈
(𝑥 ∩ 𝑦)(𝜑 ∧ 𝜓) ↔ (∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜑 ∧ ∀𝑘 ∈ (𝑥 ∩ 𝑦)𝜓)) | 
| 22 | 20, 21 | sylibr 134 | 
. . . . . . . . 9
⊢
((∀𝑘 ∈
𝑥 𝜑 ∧ ∀𝑘 ∈ 𝑦 𝜓) → ∀𝑘 ∈ (𝑥 ∩ 𝑦)(𝜑 ∧ 𝜓)) | 
| 23 |   | raleq 2693 | 
. . . . . . . . . 10
⊢ (𝑧 = (𝑥 ∩ 𝑦) → (∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓) ↔ ∀𝑘 ∈ (𝑥 ∩ 𝑦)(𝜑 ∧ 𝜓))) | 
| 24 | 23 | rspcev 2868 | 
. . . . . . . . 9
⊢ (((𝑥 ∩ 𝑦) ∈ ran ℤ≥ ∧
∀𝑘 ∈ (𝑥 ∩ 𝑦)(𝜑 ∧ 𝜓)) → ∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓)) | 
| 25 | 13, 22, 24 | syl2an 289 | 
. . . . . . . 8
⊢ (((𝑥 ∈ ran
ℤ≥ ∧ 𝑦 ∈ ran ℤ≥) ∧
(∀𝑘 ∈ 𝑥 𝜑 ∧ ∀𝑘 ∈ 𝑦 𝜓)) → ∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓)) | 
| 26 | 25 | an4s 588 | 
. . . . . . 7
⊢ (((𝑥 ∈ ran
ℤ≥ ∧ ∀𝑘 ∈ 𝑥 𝜑) ∧ (𝑦 ∈ ran ℤ≥ ∧
∀𝑘 ∈ 𝑦 𝜓)) → ∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓)) | 
| 27 | 26 | rexlimdvaa 2615 | 
. . . . . 6
⊢ ((𝑥 ∈ ran
ℤ≥ ∧ ∀𝑘 ∈ 𝑥 𝜑) → (∃𝑦 ∈ ran
ℤ≥∀𝑘 ∈ 𝑦 𝜓 → ∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓))) | 
| 28 | 27 | rexlimiva 2609 | 
. . . . 5
⊢
(∃𝑥 ∈ ran
ℤ≥∀𝑘 ∈ 𝑥 𝜑 → (∃𝑦 ∈ ran
ℤ≥∀𝑘 ∈ 𝑦 𝜓 → ∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓))) | 
| 29 | 28 | imp 124 | 
. . . 4
⊢
((∃𝑥 ∈
ran ℤ≥∀𝑘 ∈ 𝑥 𝜑 ∧ ∃𝑦 ∈ ran
ℤ≥∀𝑘 ∈ 𝑦 𝜓) → ∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓)) | 
| 30 |   | raleq 2693 | 
. . . . . 6
⊢ (𝑧 =
(ℤ≥‘𝑗) → (∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓) ↔ ∀𝑘 ∈ (ℤ≥‘𝑗)(𝜑 ∧ 𝜓))) | 
| 31 | 30 | rexrn 5699 | 
. . . . 5
⊢
(ℤ≥ Fn ℤ → (∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓) ↔ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)(𝜑 ∧ 𝜓))) | 
| 32 | 5, 6, 31 | mp2b 8 | 
. . . 4
⊢
(∃𝑧 ∈ ran
ℤ≥∀𝑘 ∈ 𝑧 (𝜑 ∧ 𝜓) ↔ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)(𝜑 ∧ 𝜓)) | 
| 33 | 29, 32 | sylib 122 | 
. . 3
⊢
((∃𝑥 ∈
ran ℤ≥∀𝑘 ∈ 𝑥 𝜑 ∧ ∃𝑦 ∈ ran
ℤ≥∀𝑘 ∈ 𝑦 𝜓) → ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)(𝜑 ∧ 𝜓)) | 
| 34 | 9, 12, 33 | syl2anbr 292 | 
. 2
⊢
((∃𝑗 ∈
ℤ ∀𝑘 ∈
(ℤ≥‘𝑗)𝜑 ∧ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓) → ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)(𝜑 ∧ 𝜓)) | 
| 35 | 4, 34 | impbii 126 | 
1
⊢
(∃𝑗 ∈
ℤ ∀𝑘 ∈
(ℤ≥‘𝑗)(𝜑 ∧ 𝜓) ↔ (∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜑 ∧ ∃𝑗 ∈ ℤ ∀𝑘 ∈ (ℤ≥‘𝑗)𝜓)) |