| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | peano2 7913 | . . . . . . . . . 10
⊢ (𝑁 ∈ ω → suc 𝑁 ∈
ω) | 
| 2 | 1 | adantr 480 | . . . . . . . . 9
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ suc 𝑁 ∈
ω) | 
| 3 |  | 1on 8519 | . . . . . . . . . . . . 13
⊢
1o ∈ On | 
| 4 | 3 | onordi 6494 | . . . . . . . . . . . 12
⊢ Ord
1o | 
| 5 |  | nnord 7896 | . . . . . . . . . . . 12
⊢ (𝑁 ∈ ω → Ord 𝑁) | 
| 6 |  | ordsseleq 6412 | . . . . . . . . . . . 12
⊢ ((Ord
1o ∧ Ord 𝑁)
→ (1o ⊆ 𝑁 ↔ (1o ∈ 𝑁 ∨ 1o = 𝑁))) | 
| 7 | 4, 5, 6 | sylancr 587 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ω →
(1o ⊆ 𝑁
↔ (1o ∈ 𝑁 ∨ 1o = 𝑁))) | 
| 8 | 7 | biimpa 476 | . . . . . . . . . 10
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (1o ∈ 𝑁 ∨ 1o = 𝑁)) | 
| 9 |  | elelsuc 6456 | . . . . . . . . . . . . 13
⊢
(1o ∈ 𝑁 → 1o ∈ suc 𝑁) | 
| 10 | 9 | a1i 11 | . . . . . . . . . . . 12
⊢ (𝑁 ∈ ω →
(1o ∈ 𝑁
→ 1o ∈ suc 𝑁)) | 
| 11 |  | sucidg 6464 | . . . . . . . . . . . . 13
⊢ (𝑁 ∈ ω → 𝑁 ∈ suc 𝑁) | 
| 12 |  | eleq1 2828 | . . . . . . . . . . . . 13
⊢
(1o = 𝑁
→ (1o ∈ suc 𝑁 ↔ 𝑁 ∈ suc 𝑁)) | 
| 13 | 11, 12 | syl5ibrcom 247 | . . . . . . . . . . . 12
⊢ (𝑁 ∈ ω →
(1o = 𝑁 →
1o ∈ suc 𝑁)) | 
| 14 | 10, 13 | jaod 859 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ω →
((1o ∈ 𝑁
∨ 1o = 𝑁)
→ 1o ∈ suc 𝑁)) | 
| 15 | 14 | adantr 480 | . . . . . . . . . 10
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ ((1o ∈ 𝑁 ∨ 1o = 𝑁) → 1o ∈ suc 𝑁)) | 
| 16 | 8, 15 | mpd 15 | . . . . . . . . 9
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ 1o ∈ suc 𝑁) | 
| 17 |  | finxpsuclem.1 | . . . . . . . . . 10
⊢ 𝐹 = (𝑛 ∈ ω, 𝑥 ∈ V ↦ if((𝑛 = 1o ∧ 𝑥 ∈ 𝑈), ∅, if(𝑥 ∈ (V × 𝑈), 〈∪ 𝑛, (1st ‘𝑥)〉, 〈𝑛, 𝑥〉))) | 
| 18 | 17 | finxpreclem6 37398 | . . . . . . . . 9
⊢ ((suc
𝑁 ∈ ω ∧
1o ∈ suc 𝑁)
→ (𝑈↑↑suc
𝑁) ⊆ (V × 𝑈)) | 
| 19 | 2, 16, 18 | syl2anc 584 | . . . . . . . 8
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑈↑↑suc
𝑁) ⊆ (V × 𝑈)) | 
| 20 | 19 | sselda 3982 | . . . . . . 7
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (𝑈↑↑suc 𝑁)) → 𝑦 ∈ (V × 𝑈)) | 
| 21 | 1 | ad2antrr 726 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → suc 𝑁 ∈
ω) | 
| 22 |  | df-2o 8508 | . . . . . . . . . . . . . . 15
⊢
2o = suc 1o | 
| 23 |  | ordsucsssuc 7844 | . . . . . . . . . . . . . . . . 17
⊢ ((Ord
1o ∧ Ord 𝑁)
→ (1o ⊆ 𝑁 ↔ suc 1o ⊆ suc 𝑁)) | 
| 24 | 4, 5, 23 | sylancr 587 | . . . . . . . . . . . . . . . 16
⊢ (𝑁 ∈ ω →
(1o ⊆ 𝑁
↔ suc 1o ⊆ suc 𝑁)) | 
| 25 | 24 | biimpa 476 | . . . . . . . . . . . . . . 15
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ suc 1o ⊆ suc 𝑁) | 
| 26 | 22, 25 | eqsstrid 4021 | . . . . . . . . . . . . . 14
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ 2o ⊆ suc 𝑁) | 
| 27 | 26 | adantr 480 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → 2o
⊆ suc 𝑁) | 
| 28 |  | simpr 484 | . . . . . . . . . . . . 13
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → 𝑦 ∈ (V × 𝑈)) | 
| 29 | 17 | finxpreclem4 37396 | . . . . . . . . . . . . 13
⊢ (((suc
𝑁 ∈ ω ∧
2o ⊆ suc 𝑁) ∧ 𝑦 ∈ (V × 𝑈)) → (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁) = (rec(𝐹, 〈∪ suc
𝑁, (1st
‘𝑦)〉)‘∪
suc 𝑁)) | 
| 30 | 21, 27, 28, 29 | syl21anc 837 | . . . . . . . . . . . 12
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁) = (rec(𝐹, 〈∪ suc
𝑁, (1st
‘𝑦)〉)‘∪
suc 𝑁)) | 
| 31 |  | ordunisuc 7853 | . . . . . . . . . . . . . . . 16
⊢ (Ord
𝑁 → ∪ suc 𝑁 = 𝑁) | 
| 32 | 5, 31 | syl 17 | . . . . . . . . . . . . . . 15
⊢ (𝑁 ∈ ω → ∪ suc 𝑁 = 𝑁) | 
| 33 |  | opeq1 4872 | . . . . . . . . . . . . . . . 16
⊢ (∪ suc 𝑁 = 𝑁 → 〈∪
suc 𝑁, (1st
‘𝑦)〉 =
〈𝑁, (1st
‘𝑦)〉) | 
| 34 |  | rdgeq2 8453 | . . . . . . . . . . . . . . . 16
⊢
(〈∪ suc 𝑁, (1st ‘𝑦)〉 = 〈𝑁, (1st ‘𝑦)〉 → rec(𝐹, 〈∪ suc
𝑁, (1st
‘𝑦)〉) =
rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)) | 
| 35 | 33, 34 | syl 17 | . . . . . . . . . . . . . . 15
⊢ (∪ suc 𝑁 = 𝑁 → rec(𝐹, 〈∪ suc
𝑁, (1st
‘𝑦)〉) =
rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)) | 
| 36 | 32, 35 | syl 17 | . . . . . . . . . . . . . 14
⊢ (𝑁 ∈ ω → rec(𝐹, 〈∪ suc 𝑁, (1st ‘𝑦)〉) = rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)) | 
| 37 | 36, 32 | fveq12d 6912 | . . . . . . . . . . . . 13
⊢ (𝑁 ∈ ω →
(rec(𝐹, 〈∪ suc 𝑁, (1st ‘𝑦)〉)‘∪
suc 𝑁) = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁)) | 
| 38 | 37 | ad2antrr 726 | . . . . . . . . . . . 12
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (rec(𝐹, 〈∪ suc 𝑁, (1st ‘𝑦)〉)‘∪
suc 𝑁) = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁)) | 
| 39 | 30, 38 | eqtrd 2776 | . . . . . . . . . . 11
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁) = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁)) | 
| 40 | 39 | eqeq2d 2747 | . . . . . . . . . 10
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (∅ =
(rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁) ↔ ∅ = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁))) | 
| 41 | 17 | dffinxpf 37387 | . . . . . . . . . . . . 13
⊢ (𝑈↑↑suc 𝑁) = {𝑦 ∣ (suc 𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁))} | 
| 42 | 41 | eqabri 2884 | . . . . . . . . . . . 12
⊢ (𝑦 ∈ (𝑈↑↑suc 𝑁) ↔ (suc 𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁))) | 
| 43 | 1 | biantrurd 532 | . . . . . . . . . . . 12
⊢ (𝑁 ∈ ω → (∅
= (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁) ↔ (suc 𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁)))) | 
| 44 | 42, 43 | bitr4id 290 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ω → (𝑦 ∈ (𝑈↑↑suc 𝑁) ↔ ∅ = (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁))) | 
| 45 | 44 | ad2antrr 726 | . . . . . . . . . 10
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (𝑦 ∈ (𝑈↑↑suc 𝑁) ↔ ∅ = (rec(𝐹, 〈suc 𝑁, 𝑦〉)‘suc 𝑁))) | 
| 46 |  | fvex 6918 | . . . . . . . . . . . . 13
⊢
(1st ‘𝑦) ∈ V | 
| 47 |  | opeq2 4873 | . . . . . . . . . . . . . . . . 17
⊢ (𝑧 = (1st ‘𝑦) → 〈𝑁, 𝑧〉 = 〈𝑁, (1st ‘𝑦)〉) | 
| 48 |  | rdgeq2 8453 | . . . . . . . . . . . . . . . . 17
⊢
(〈𝑁, 𝑧〉 = 〈𝑁, (1st ‘𝑦)〉 → rec(𝐹, 〈𝑁, 𝑧〉) = rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)) | 
| 49 | 47, 48 | syl 17 | . . . . . . . . . . . . . . . 16
⊢ (𝑧 = (1st ‘𝑦) → rec(𝐹, 〈𝑁, 𝑧〉) = rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)) | 
| 50 | 49 | fveq1d 6907 | . . . . . . . . . . . . . . 15
⊢ (𝑧 = (1st ‘𝑦) → (rec(𝐹, 〈𝑁, 𝑧〉)‘𝑁) = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁)) | 
| 51 | 50 | eqeq2d 2747 | . . . . . . . . . . . . . 14
⊢ (𝑧 = (1st ‘𝑦) → (∅ = (rec(𝐹, 〈𝑁, 𝑧〉)‘𝑁) ↔ ∅ = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁))) | 
| 52 | 51 | anbi2d 630 | . . . . . . . . . . . . 13
⊢ (𝑧 = (1st ‘𝑦) → ((𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈𝑁, 𝑧〉)‘𝑁)) ↔ (𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁)))) | 
| 53 | 17 | dffinxpf 37387 | . . . . . . . . . . . . 13
⊢ (𝑈↑↑𝑁) = {𝑧 ∣ (𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈𝑁, 𝑧〉)‘𝑁))} | 
| 54 | 46, 52, 53 | elab2 3681 | . . . . . . . . . . . 12
⊢
((1st ‘𝑦) ∈ (𝑈↑↑𝑁) ↔ (𝑁 ∈ ω ∧ ∅ = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁))) | 
| 55 | 54 | baib 535 | . . . . . . . . . . 11
⊢ (𝑁 ∈ ω →
((1st ‘𝑦)
∈ (𝑈↑↑𝑁) ↔ ∅ = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁))) | 
| 56 | 55 | ad2antrr 726 | . . . . . . . . . 10
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → ((1st
‘𝑦) ∈ (𝑈↑↑𝑁) ↔ ∅ = (rec(𝐹, 〈𝑁, (1st ‘𝑦)〉)‘𝑁))) | 
| 57 | 40, 45, 56 | 3bitr4d 311 | . . . . . . . . 9
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (𝑦 ∈ (𝑈↑↑suc 𝑁) ↔ (1st ‘𝑦) ∈ (𝑈↑↑𝑁))) | 
| 58 | 57 | biimpd 229 | . . . . . . . 8
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (V ×
𝑈)) → (𝑦 ∈ (𝑈↑↑suc 𝑁) → (1st ‘𝑦) ∈ (𝑈↑↑𝑁))) | 
| 59 | 58 | impancom 451 | . . . . . . 7
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (𝑈↑↑suc 𝑁)) → (𝑦 ∈ (V × 𝑈) → (1st ‘𝑦) ∈ (𝑈↑↑𝑁))) | 
| 60 | 20, 59 | mpd 15 | . . . . . 6
⊢ (((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
∧ 𝑦 ∈ (𝑈↑↑suc 𝑁)) → (1st
‘𝑦) ∈ (𝑈↑↑𝑁)) | 
| 61 | 60 | ex 412 | . . . . 5
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑦 ∈ (𝑈↑↑suc 𝑁) → (1st
‘𝑦) ∈ (𝑈↑↑𝑁))) | 
| 62 | 20 | ex 412 | . . . . 5
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑦 ∈ (𝑈↑↑suc 𝑁) → 𝑦 ∈ (V × 𝑈))) | 
| 63 | 61, 62 | jcad 512 | . . . 4
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑦 ∈ (𝑈↑↑suc 𝑁) → ((1st
‘𝑦) ∈ (𝑈↑↑𝑁) ∧ 𝑦 ∈ (V × 𝑈)))) | 
| 64 | 57 | exbiri 810 | . . . . . 6
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑦 ∈ (V ×
𝑈) → ((1st
‘𝑦) ∈ (𝑈↑↑𝑁) → 𝑦 ∈ (𝑈↑↑suc 𝑁)))) | 
| 65 | 64 | impd 410 | . . . . 5
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ ((𝑦 ∈ (V
× 𝑈) ∧
(1st ‘𝑦)
∈ (𝑈↑↑𝑁)) → 𝑦 ∈ (𝑈↑↑suc 𝑁))) | 
| 66 | 65 | ancomsd 465 | . . . 4
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (((1st ‘𝑦) ∈ (𝑈↑↑𝑁) ∧ 𝑦 ∈ (V × 𝑈)) → 𝑦 ∈ (𝑈↑↑suc 𝑁))) | 
| 67 | 63, 66 | impbid 212 | . . 3
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑦 ∈ (𝑈↑↑suc 𝑁) ↔ ((1st
‘𝑦) ∈ (𝑈↑↑𝑁) ∧ 𝑦 ∈ (V × 𝑈)))) | 
| 68 |  | elxp8 37373 | . . 3
⊢ (𝑦 ∈ ((𝑈↑↑𝑁) × 𝑈) ↔ ((1st ‘𝑦) ∈ (𝑈↑↑𝑁) ∧ 𝑦 ∈ (V × 𝑈))) | 
| 69 | 67, 68 | bitr4di 289 | . 2
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑦 ∈ (𝑈↑↑suc 𝑁) ↔ 𝑦 ∈ ((𝑈↑↑𝑁) × 𝑈))) | 
| 70 | 69 | eqrdv 2734 | 1
⊢ ((𝑁 ∈ ω ∧
1o ⊆ 𝑁)
→ (𝑈↑↑suc
𝑁) = ((𝑈↑↑𝑁) × 𝑈)) |