Proof of Theorem 1fv
| Step | Hyp | Ref
 | Expression | 
| 1 |   | 0z 9337 | 
. . . . . 6
⊢ 0 ∈
ℤ | 
| 2 |   | f1osng 5545 | 
. . . . . 6
⊢ ((0
∈ ℤ ∧ 𝑁
∈ 𝑉) → {〈0,
𝑁〉}:{0}–1-1-onto→{𝑁}) | 
| 3 | 1, 2 | mpan 424 | 
. . . . 5
⊢ (𝑁 ∈ 𝑉 → {〈0, 𝑁〉}:{0}–1-1-onto→{𝑁}) | 
| 4 |   | f1ofo 5511 | 
. . . . . 6
⊢
({〈0, 𝑁〉}:{0}–1-1-onto→{𝑁} → {〈0, 𝑁〉}:{0}–onto→{𝑁}) | 
| 5 |   | dffo2 5484 | 
. . . . . . 7
⊢
({〈0, 𝑁〉}:{0}–onto→{𝑁} ↔ ({〈0, 𝑁〉}:{0}⟶{𝑁} ∧ ran {〈0, 𝑁〉} = {𝑁})) | 
| 6 | 5 | biimpi 120 | 
. . . . . 6
⊢
({〈0, 𝑁〉}:{0}–onto→{𝑁} → ({〈0, 𝑁〉}:{0}⟶{𝑁} ∧ ran {〈0, 𝑁〉} = {𝑁})) | 
| 7 |   | fzsn 10141 | 
. . . . . . . . . . . . 13
⊢ (0 ∈
ℤ → (0...0) = {0}) | 
| 8 | 1, 7 | ax-mp 5 | 
. . . . . . . . . . . 12
⊢ (0...0) =
{0} | 
| 9 | 8 | eqcomi 2200 | 
. . . . . . . . . . 11
⊢ {0} =
(0...0) | 
| 10 | 9 | feq2i 5401 | 
. . . . . . . . . 10
⊢
({〈0, 𝑁〉}:{0}⟶{𝑁} ↔ {〈0, 𝑁〉}:(0...0)⟶{𝑁}) | 
| 11 | 10 | biimpi 120 | 
. . . . . . . . 9
⊢
({〈0, 𝑁〉}:{0}⟶{𝑁} → {〈0, 𝑁〉}:(0...0)⟶{𝑁}) | 
| 12 |   | snssi 3766 | 
. . . . . . . . 9
⊢ (𝑁 ∈ 𝑉 → {𝑁} ⊆ 𝑉) | 
| 13 |   | fss 5419 | 
. . . . . . . . 9
⊢
(({〈0, 𝑁〉}:(0...0)⟶{𝑁} ∧ {𝑁} ⊆ 𝑉) → {〈0, 𝑁〉}:(0...0)⟶𝑉) | 
| 14 | 11, 12, 13 | syl2an 289 | 
. . . . . . . 8
⊢
(({〈0, 𝑁〉}:{0}⟶{𝑁} ∧ 𝑁 ∈ 𝑉) → {〈0, 𝑁〉}:(0...0)⟶𝑉) | 
| 15 | 14 | ex 115 | 
. . . . . . 7
⊢
({〈0, 𝑁〉}:{0}⟶{𝑁} → (𝑁 ∈ 𝑉 → {〈0, 𝑁〉}:(0...0)⟶𝑉)) | 
| 16 | 15 | adantr 276 | 
. . . . . 6
⊢
(({〈0, 𝑁〉}:{0}⟶{𝑁} ∧ ran {〈0, 𝑁〉} = {𝑁}) → (𝑁 ∈ 𝑉 → {〈0, 𝑁〉}:(0...0)⟶𝑉)) | 
| 17 | 4, 6, 16 | 3syl 17 | 
. . . . 5
⊢
({〈0, 𝑁〉}:{0}–1-1-onto→{𝑁} → (𝑁 ∈ 𝑉 → {〈0, 𝑁〉}:(0...0)⟶𝑉)) | 
| 18 | 3, 17 | mpcom 36 | 
. . . 4
⊢ (𝑁 ∈ 𝑉 → {〈0, 𝑁〉}:(0...0)⟶𝑉) | 
| 19 |   | fvsng 5758 | 
. . . . 5
⊢ ((0
∈ ℤ ∧ 𝑁
∈ 𝑉) → ({〈0,
𝑁〉}‘0) = 𝑁) | 
| 20 | 1, 19 | mpan 424 | 
. . . 4
⊢ (𝑁 ∈ 𝑉 → ({〈0, 𝑁〉}‘0) = 𝑁) | 
| 21 | 18, 20 | jca 306 | 
. . 3
⊢ (𝑁 ∈ 𝑉 → ({〈0, 𝑁〉}:(0...0)⟶𝑉 ∧ ({〈0, 𝑁〉}‘0) = 𝑁)) | 
| 22 | 21 | adantr 276 | 
. 2
⊢ ((𝑁 ∈ 𝑉 ∧ 𝑃 = {〈0, 𝑁〉}) → ({〈0, 𝑁〉}:(0...0)⟶𝑉 ∧ ({〈0, 𝑁〉}‘0) = 𝑁)) | 
| 23 |   | feq1 5390 | 
. . . 4
⊢ (𝑃 = {〈0, 𝑁〉} → (𝑃:(0...0)⟶𝑉 ↔ {〈0, 𝑁〉}:(0...0)⟶𝑉)) | 
| 24 |   | fveq1 5557 | 
. . . . 5
⊢ (𝑃 = {〈0, 𝑁〉} → (𝑃‘0) = ({〈0, 𝑁〉}‘0)) | 
| 25 | 24 | eqeq1d 2205 | 
. . . 4
⊢ (𝑃 = {〈0, 𝑁〉} → ((𝑃‘0) = 𝑁 ↔ ({〈0, 𝑁〉}‘0) = 𝑁)) | 
| 26 | 23, 25 | anbi12d 473 | 
. . 3
⊢ (𝑃 = {〈0, 𝑁〉} → ((𝑃:(0...0)⟶𝑉 ∧ (𝑃‘0) = 𝑁) ↔ ({〈0, 𝑁〉}:(0...0)⟶𝑉 ∧ ({〈0, 𝑁〉}‘0) = 𝑁))) | 
| 27 | 26 | adantl 277 | 
. 2
⊢ ((𝑁 ∈ 𝑉 ∧ 𝑃 = {〈0, 𝑁〉}) → ((𝑃:(0...0)⟶𝑉 ∧ (𝑃‘0) = 𝑁) ↔ ({〈0, 𝑁〉}:(0...0)⟶𝑉 ∧ ({〈0, 𝑁〉}‘0) = 𝑁))) | 
| 28 | 22, 27 | mpbird 167 | 
1
⊢ ((𝑁 ∈ 𝑉 ∧ 𝑃 = {〈0, 𝑁〉}) → (𝑃:(0...0)⟶𝑉 ∧ (𝑃‘0) = 𝑁)) |