| Step | Hyp | Ref
 | Expression | 
| 1 |   | unrab 3434 | 
. . 3
⊢ ({𝑧 ∈ ℤ ∣ 𝑧 ∈ ℕ} ∪ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}) =
{𝑧 ∈ ℤ ∣
(𝑧 ∈ ℕ ∨
-𝑧 ∈
ℕ0)} | 
| 2 |   | nnssz 9343 | 
. . . . . 6
⊢ ℕ
⊆ ℤ | 
| 3 |   | dfss1 3367 | 
. . . . . 6
⊢ (ℕ
⊆ ℤ ↔ (ℤ ∩ ℕ) = ℕ) | 
| 4 | 2, 3 | mpbi 145 | 
. . . . 5
⊢ (ℤ
∩ ℕ) = ℕ | 
| 5 |   | dfin5 3164 | 
. . . . 5
⊢ (ℤ
∩ ℕ) = {𝑧 ∈
ℤ ∣ 𝑧 ∈
ℕ} | 
| 6 | 4, 5 | eqtr3i 2219 | 
. . . 4
⊢ ℕ =
{𝑧 ∈ ℤ ∣
𝑧 ∈
ℕ} | 
| 7 | 6 | uneq1i 3313 | 
. . 3
⊢ (ℕ
∪ {𝑧 ∈ ℤ
∣ -𝑧 ∈
ℕ0}) = ({𝑧
∈ ℤ ∣ 𝑧
∈ ℕ} ∪ {𝑧
∈ ℤ ∣ -𝑧
∈ ℕ0}) | 
| 8 |   | rabid2 2674 | 
. . . 4
⊢ (ℤ
= {𝑧 ∈ ℤ ∣
(𝑧 ∈ ℕ ∨
-𝑧 ∈
ℕ0)} ↔ ∀𝑧 ∈ ℤ (𝑧 ∈ ℕ ∨ -𝑧 ∈
ℕ0)) | 
| 9 |   | elznn 9342 | 
. . . . 5
⊢ (𝑧 ∈ ℤ ↔ (𝑧 ∈ ℝ ∧ (𝑧 ∈ ℕ ∨ -𝑧 ∈
ℕ0))) | 
| 10 | 9 | simprbi 275 | 
. . . 4
⊢ (𝑧 ∈ ℤ → (𝑧 ∈ ℕ ∨ -𝑧 ∈
ℕ0)) | 
| 11 | 8, 10 | mprgbir 2555 | 
. . 3
⊢ ℤ =
{𝑧 ∈ ℤ ∣
(𝑧 ∈ ℕ ∨
-𝑧 ∈
ℕ0)} | 
| 12 | 1, 7, 11 | 3eqtr4ri 2228 | 
. 2
⊢ ℤ =
(ℕ ∪ {𝑧 ∈
ℤ ∣ -𝑧 ∈
ℕ0}) | 
| 13 |   | nnex 8996 | 
. . . 4
⊢ ℕ
∈ V | 
| 14 | 13 | enref 6824 | 
. . 3
⊢ ℕ
≈ ℕ | 
| 15 |   | zex 9335 | 
. . . . . 6
⊢ ℤ
∈ V | 
| 16 | 15 | rabex 4177 | 
. . . . 5
⊢ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}
∈ V | 
| 17 |   | nn0ex 9255 | 
. . . . 5
⊢
ℕ0 ∈ V | 
| 18 |   | negeq 8219 | 
. . . . . . . 8
⊢ (𝑧 = 𝑥 → -𝑧 = -𝑥) | 
| 19 | 18 | eleq1d 2265 | 
. . . . . . 7
⊢ (𝑧 = 𝑥 → (-𝑧 ∈ ℕ0 ↔ -𝑥 ∈
ℕ0)) | 
| 20 | 19 | elrab 2920 | 
. . . . . 6
⊢ (𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} ↔ (𝑥 ∈ ℤ ∧ -𝑥 ∈
ℕ0)) | 
| 21 | 20 | simprbi 275 | 
. . . . 5
⊢ (𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} → -𝑥 ∈
ℕ0) | 
| 22 |   | negeq 8219 | 
. . . . . . 7
⊢ (𝑧 = -𝑦 → -𝑧 = --𝑦) | 
| 23 | 22 | eleq1d 2265 | 
. . . . . 6
⊢ (𝑧 = -𝑦 → (-𝑧 ∈ ℕ0 ↔ --𝑦 ∈
ℕ0)) | 
| 24 |   | nn0negz 9360 | 
. . . . . 6
⊢ (𝑦 ∈ ℕ0
→ -𝑦 ∈
ℤ) | 
| 25 |   | nn0cn 9259 | 
. . . . . . . . 9
⊢ (𝑦 ∈ ℕ0
→ 𝑦 ∈
ℂ) | 
| 26 | 25 | negnegd 8328 | 
. . . . . . . 8
⊢ (𝑦 ∈ ℕ0
→ --𝑦 = 𝑦) | 
| 27 | 26 | eleq1d 2265 | 
. . . . . . 7
⊢ (𝑦 ∈ ℕ0
→ (--𝑦 ∈
ℕ0 ↔ 𝑦 ∈
ℕ0)) | 
| 28 | 27 | ibir 177 | 
. . . . . 6
⊢ (𝑦 ∈ ℕ0
→ --𝑦 ∈
ℕ0) | 
| 29 | 23, 24, 28 | elrabd 2922 | 
. . . . 5
⊢ (𝑦 ∈ ℕ0
→ -𝑦 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈
ℕ0}) | 
| 30 |   | elrabi 2917 | 
. . . . . . . 8
⊢ (𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} → 𝑥 ∈
ℤ) | 
| 31 | 30 | adantr 276 | 
. . . . . . 7
⊢ ((𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} ∧ 𝑦 ∈ ℕ0)
→ 𝑥 ∈
ℤ) | 
| 32 | 31 | zcnd 9449 | 
. . . . . 6
⊢ ((𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} ∧ 𝑦 ∈ ℕ0)
→ 𝑥 ∈
ℂ) | 
| 33 | 25 | adantl 277 | 
. . . . . 6
⊢ ((𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} ∧ 𝑦 ∈ ℕ0)
→ 𝑦 ∈
ℂ) | 
| 34 |   | negcon2 8279 | 
. . . . . 6
⊢ ((𝑥 ∈ ℂ ∧ 𝑦 ∈ ℂ) → (𝑥 = -𝑦 ↔ 𝑦 = -𝑥)) | 
| 35 | 32, 33, 34 | syl2anc 411 | 
. . . . 5
⊢ ((𝑥 ∈ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0} ∧ 𝑦 ∈ ℕ0)
→ (𝑥 = -𝑦 ↔ 𝑦 = -𝑥)) | 
| 36 | 16, 17, 21, 29, 35 | en3i 6830 | 
. . . 4
⊢ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}
≈ ℕ0 | 
| 37 |   | nn0ennn 10525 | 
. . . 4
⊢
ℕ0 ≈ ℕ | 
| 38 | 36, 37 | entri 6845 | 
. . 3
⊢ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}
≈ ℕ | 
| 39 |   | inrab2 3436 | 
. . . 4
⊢ ({𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}
∩ ℕ) = {𝑧 ∈
(ℤ ∩ ℕ) ∣ -𝑧 ∈ ℕ0} | 
| 40 |   | incom 3355 | 
. . . 4
⊢ ({𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}
∩ ℕ) = (ℕ ∩ {𝑧 ∈ ℤ ∣ -𝑧 ∈
ℕ0}) | 
| 41 |   | rabeq0 3480 | 
. . . . 5
⊢ ({𝑧 ∈ (ℤ ∩ ℕ)
∣ -𝑧 ∈
ℕ0} = ∅ ↔ ∀𝑧 ∈ (ℤ ∩ ℕ) ¬ -𝑧 ∈
ℕ0) | 
| 42 |   | 0red 8027 | 
. . . . . . . 8
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 0 ∈ ℝ) | 
| 43 |   | simpl 109 | 
. . . . . . . . 9
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 𝑧 ∈
ℕ) | 
| 44 | 43 | nnred 9003 | 
. . . . . . . 8
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 𝑧 ∈
ℝ) | 
| 45 |   | nngt0 9015 | 
. . . . . . . . 9
⊢ (𝑧 ∈ ℕ → 0 <
𝑧) | 
| 46 | 45 | adantr 276 | 
. . . . . . . 8
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 0 < 𝑧) | 
| 47 |   | nn0ge0 9274 | 
. . . . . . . . . 10
⊢ (-𝑧 ∈ ℕ0
→ 0 ≤ -𝑧) | 
| 48 | 47 | adantl 277 | 
. . . . . . . . 9
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 0 ≤ -𝑧) | 
| 49 | 44 | le0neg1d 8544 | 
. . . . . . . . 9
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ (𝑧 ≤ 0 ↔ 0
≤ -𝑧)) | 
| 50 | 48, 49 | mpbird 167 | 
. . . . . . . 8
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 𝑧 ≤
0) | 
| 51 | 42, 44, 42, 46, 50 | ltletrd 8450 | 
. . . . . . 7
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ 0 < 0) | 
| 52 | 42 | ltnrd 8138 | 
. . . . . . 7
⊢ ((𝑧 ∈ ℕ ∧ -𝑧 ∈ ℕ0)
→ ¬ 0 < 0) | 
| 53 | 51, 52 | pm2.65da 662 | 
. . . . . 6
⊢ (𝑧 ∈ ℕ → ¬
-𝑧 ∈
ℕ0) | 
| 54 | 53, 4 | eleq2s 2291 | 
. . . . 5
⊢ (𝑧 ∈ (ℤ ∩ ℕ)
→ ¬ -𝑧 ∈
ℕ0) | 
| 55 | 41, 54 | mprgbir 2555 | 
. . . 4
⊢ {𝑧 ∈ (ℤ ∩ ℕ)
∣ -𝑧 ∈
ℕ0} = ∅ | 
| 56 | 39, 40, 55 | 3eqtr3i 2225 | 
. . 3
⊢ (ℕ
∩ {𝑧 ∈ ℤ
∣ -𝑧 ∈
ℕ0}) = ∅ | 
| 57 |   | unennn 12614 | 
. . 3
⊢ ((ℕ
≈ ℕ ∧ {𝑧
∈ ℤ ∣ -𝑧
∈ ℕ0} ≈ ℕ ∧ (ℕ ∩ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}) =
∅) → (ℕ ∪ {𝑧 ∈ ℤ ∣ -𝑧 ∈ ℕ0}) ≈
ℕ) | 
| 58 | 14, 38, 56, 57 | mp3an 1348 | 
. 2
⊢ (ℕ
∪ {𝑧 ∈ ℤ
∣ -𝑧 ∈
ℕ0}) ≈ ℕ | 
| 59 | 12, 58 | eqbrtri 4054 | 
1
⊢ ℤ
≈ ℕ |