| Step | Hyp | Ref
| Expression |
| 1 | | 012of.g |
. . . . . 6
⊢ 𝐺 = frec((𝑥 ∈ ℤ ↦ (𝑥 + 1)), 0) |
| 2 | 1 | frechashgf1o 10520 |
. . . . 5
⊢ 𝐺:ω–1-1-onto→ℕ0 |
| 3 | | f1ocnv 5517 |
. . . . 5
⊢ (𝐺:ω–1-1-onto→ℕ0 → ◡𝐺:ℕ0–1-1-onto→ω) |
| 4 | | f1of 5504 |
. . . . 5
⊢ (◡𝐺:ℕ0–1-1-onto→ω → ◡𝐺:ℕ0⟶ω) |
| 5 | 2, 3, 4 | mp2b 8 |
. . . 4
⊢ ◡𝐺:ℕ0⟶ω |
| 6 | | 0nn0 9264 |
. . . . 5
⊢ 0 ∈
ℕ0 |
| 7 | | 1nn0 9265 |
. . . . 5
⊢ 1 ∈
ℕ0 |
| 8 | | prssi 3780 |
. . . . 5
⊢ ((0
∈ ℕ0 ∧ 1 ∈ ℕ0) → {0, 1}
⊆ ℕ0) |
| 9 | 6, 7, 8 | mp2an 426 |
. . . 4
⊢ {0, 1}
⊆ ℕ0 |
| 10 | | fssres 5433 |
. . . 4
⊢ ((◡𝐺:ℕ0⟶ω ∧
{0, 1} ⊆ ℕ0) → (◡𝐺 ↾ {0, 1}):{0,
1}⟶ω) |
| 11 | 5, 9, 10 | mp2an 426 |
. . 3
⊢ (◡𝐺 ↾ {0, 1}):{0,
1}⟶ω |
| 12 | | ffn 5407 |
. . 3
⊢ ((◡𝐺 ↾ {0, 1}):{0, 1}⟶ω
→ (◡𝐺 ↾ {0, 1}) Fn {0, 1}) |
| 13 | 11, 12 | ax-mp 5 |
. 2
⊢ (◡𝐺 ↾ {0, 1}) Fn {0, 1} |
| 14 | | fvres 5582 |
. . . 4
⊢ (𝑗 ∈ {0, 1} → ((◡𝐺 ↾ {0, 1})‘𝑗) = (◡𝐺‘𝑗)) |
| 15 | | elpri 3645 |
. . . . 5
⊢ (𝑗 ∈ {0, 1} → (𝑗 = 0 ∨ 𝑗 = 1)) |
| 16 | | fveq2 5558 |
. . . . . . 7
⊢ (𝑗 = 0 → (◡𝐺‘𝑗) = (◡𝐺‘0)) |
| 17 | | 0zd 9338 |
. . . . . . . . . . 11
⊢ (⊤
→ 0 ∈ ℤ) |
| 18 | 17, 1 | frec2uz0d 10491 |
. . . . . . . . . 10
⊢ (⊤
→ (𝐺‘∅) =
0) |
| 19 | 18 | mptru 1373 |
. . . . . . . . 9
⊢ (𝐺‘∅) =
0 |
| 20 | | peano1 4630 |
. . . . . . . . . 10
⊢ ∅
∈ ω |
| 21 | | f1ocnvfv 5826 |
. . . . . . . . . 10
⊢ ((𝐺:ω–1-1-onto→ℕ0 ∧ ∅ ∈
ω) → ((𝐺‘∅) = 0 → (◡𝐺‘0) = ∅)) |
| 22 | 2, 20, 21 | mp2an 426 |
. . . . . . . . 9
⊢ ((𝐺‘∅) = 0 →
(◡𝐺‘0) = ∅) |
| 23 | 19, 22 | ax-mp 5 |
. . . . . . . 8
⊢ (◡𝐺‘0) = ∅ |
| 24 | | 0lt2o 6499 |
. . . . . . . 8
⊢ ∅
∈ 2o |
| 25 | 23, 24 | eqeltri 2269 |
. . . . . . 7
⊢ (◡𝐺‘0) ∈
2o |
| 26 | 16, 25 | eqeltrdi 2287 |
. . . . . 6
⊢ (𝑗 = 0 → (◡𝐺‘𝑗) ∈ 2o) |
| 27 | | fveq2 5558 |
. . . . . . 7
⊢ (𝑗 = 1 → (◡𝐺‘𝑗) = (◡𝐺‘1)) |
| 28 | | df-1o 6474 |
. . . . . . . . . . 11
⊢
1o = suc ∅ |
| 29 | 28 | fveq2i 5561 |
. . . . . . . . . 10
⊢ (𝐺‘1o) = (𝐺‘suc
∅) |
| 30 | 20 | a1i 9 |
. . . . . . . . . . . 12
⊢ (⊤
→ ∅ ∈ ω) |
| 31 | 17, 1, 30 | frec2uzsucd 10493 |
. . . . . . . . . . 11
⊢ (⊤
→ (𝐺‘suc
∅) = ((𝐺‘∅) + 1)) |
| 32 | 31 | mptru 1373 |
. . . . . . . . . 10
⊢ (𝐺‘suc ∅) = ((𝐺‘∅) +
1) |
| 33 | 19 | oveq1i 5932 |
. . . . . . . . . . 11
⊢ ((𝐺‘∅) + 1) = (0 +
1) |
| 34 | | 0p1e1 9104 |
. . . . . . . . . . 11
⊢ (0 + 1) =
1 |
| 35 | 33, 34 | eqtri 2217 |
. . . . . . . . . 10
⊢ ((𝐺‘∅) + 1) =
1 |
| 36 | 29, 32, 35 | 3eqtri 2221 |
. . . . . . . . 9
⊢ (𝐺‘1o) =
1 |
| 37 | | 1onn 6578 |
. . . . . . . . . 10
⊢
1o ∈ ω |
| 38 | | f1ocnvfv 5826 |
. . . . . . . . . 10
⊢ ((𝐺:ω–1-1-onto→ℕ0 ∧ 1o ∈
ω) → ((𝐺‘1o) = 1 → (◡𝐺‘1) = 1o)) |
| 39 | 2, 37, 38 | mp2an 426 |
. . . . . . . . 9
⊢ ((𝐺‘1o) = 1 →
(◡𝐺‘1) = 1o) |
| 40 | 36, 39 | ax-mp 5 |
. . . . . . . 8
⊢ (◡𝐺‘1) = 1o |
| 41 | | 1lt2o 6500 |
. . . . . . . 8
⊢
1o ∈ 2o |
| 42 | 40, 41 | eqeltri 2269 |
. . . . . . 7
⊢ (◡𝐺‘1) ∈
2o |
| 43 | 27, 42 | eqeltrdi 2287 |
. . . . . 6
⊢ (𝑗 = 1 → (◡𝐺‘𝑗) ∈ 2o) |
| 44 | 26, 43 | jaoi 717 |
. . . . 5
⊢ ((𝑗 = 0 ∨ 𝑗 = 1) → (◡𝐺‘𝑗) ∈ 2o) |
| 45 | 15, 44 | syl 14 |
. . . 4
⊢ (𝑗 ∈ {0, 1} → (◡𝐺‘𝑗) ∈ 2o) |
| 46 | 14, 45 | eqeltrd 2273 |
. . 3
⊢ (𝑗 ∈ {0, 1} → ((◡𝐺 ↾ {0, 1})‘𝑗) ∈ 2o) |
| 47 | 46 | rgen 2550 |
. 2
⊢
∀𝑗 ∈ {0,
1} ((◡𝐺 ↾ {0, 1})‘𝑗) ∈ 2o |
| 48 | | ffnfv 5720 |
. 2
⊢ ((◡𝐺 ↾ {0, 1}):{0, 1}⟶2o
↔ ((◡𝐺 ↾ {0, 1}) Fn {0, 1} ∧
∀𝑗 ∈ {0, 1}
((◡𝐺 ↾ {0, 1})‘𝑗) ∈ 2o)) |
| 49 | 13, 47, 48 | mpbir2an 944 |
1
⊢ (◡𝐺 ↾ {0, 1}):{0,
1}⟶2o |