| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | ordom 7898 | . . . . 5
⊢ Ord
ω | 
| 2 |  | ordwe 6396 | . . . . 5
⊢ (Ord
ω → E We ω) | 
| 3 | 1, 2 | ax-mp 5 | . . . 4
⊢  E We
ω | 
| 4 |  | rdgeq2 8453 | . . . . . . . . 9
⊢ (𝐴 = if(𝐴 ∈ ℤ, 𝐴, 0) → rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) = rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0))) | 
| 5 | 4 | reseq1d 5995 | . . . . . . . 8
⊢ (𝐴 = if(𝐴 ∈ ℤ, 𝐴, 0) → (rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) = (rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω)) | 
| 6 |  | isoeq1 7338 | . . . . . . . 8
⊢
((rec((𝑥 ∈ V
↦ (𝑥 + 1)), 𝐴) ↾ ω) = (rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) → ((rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) Isom E , < (ω,
(ℤ≥‘𝐴)) ↔ (rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E , <
(ω, (ℤ≥‘𝐴)))) | 
| 7 | 5, 6 | syl 17 | . . . . . . 7
⊢ (𝐴 = if(𝐴 ∈ ℤ, 𝐴, 0) → ((rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) Isom E , < (ω,
(ℤ≥‘𝐴)) ↔ (rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E , <
(ω, (ℤ≥‘𝐴)))) | 
| 8 |  | fveq2 6905 | . . . . . . . 8
⊢ (𝐴 = if(𝐴 ∈ ℤ, 𝐴, 0) →
(ℤ≥‘𝐴) = (ℤ≥‘if(𝐴 ∈ ℤ, 𝐴, 0))) | 
| 9 |  | isoeq5 7342 | . . . . . . . 8
⊢
((ℤ≥‘𝐴) = (ℤ≥‘if(𝐴 ∈ ℤ, 𝐴, 0)) → ((rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E , <
(ω, (ℤ≥‘𝐴)) ↔ (rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E , <
(ω, (ℤ≥‘if(𝐴 ∈ ℤ, 𝐴, 0))))) | 
| 10 | 8, 9 | syl 17 | . . . . . . 7
⊢ (𝐴 = if(𝐴 ∈ ℤ, 𝐴, 0) → ((rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E , <
(ω, (ℤ≥‘𝐴)) ↔ (rec((𝑥 ∈ V ↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E , <
(ω, (ℤ≥‘if(𝐴 ∈ ℤ, 𝐴, 0))))) | 
| 11 |  | 0z 12626 | . . . . . . . . 9
⊢ 0 ∈
ℤ | 
| 12 | 11 | elimel 4594 | . . . . . . . 8
⊢ if(𝐴 ∈ ℤ, 𝐴, 0) ∈
ℤ | 
| 13 |  | eqid 2736 | . . . . . . . 8
⊢
(rec((𝑥 ∈ V
↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) =
(rec((𝑥 ∈ V ↦
(𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾
ω) | 
| 14 | 12, 13 | om2uzisoi 13996 | . . . . . . 7
⊢
(rec((𝑥 ∈ V
↦ (𝑥 + 1)), if(𝐴 ∈ ℤ, 𝐴, 0)) ↾ ω) Isom E ,
< (ω, (ℤ≥‘if(𝐴 ∈ ℤ, 𝐴, 0))) | 
| 15 | 7, 10, 14 | dedth2v 4587 | . . . . . 6
⊢ (𝐴 ∈ ℤ →
(rec((𝑥 ∈ V ↦
(𝑥 + 1)), 𝐴) ↾ ω) Isom E , < (ω,
(ℤ≥‘𝐴))) | 
| 16 |  | isocnv 7351 | . . . . . 6
⊢
((rec((𝑥 ∈ V
↦ (𝑥 + 1)), 𝐴) ↾ ω) Isom E , <
(ω, (ℤ≥‘𝐴)) → ◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) Isom < , E
((ℤ≥‘𝐴), ω)) | 
| 17 | 15, 16 | syl 17 | . . . . 5
⊢ (𝐴 ∈ ℤ → ◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) Isom < , E
((ℤ≥‘𝐴), ω)) | 
| 18 |  | dmres 6029 | . . . . . . . 8
⊢ dom
(rec((𝑥 ∈ V ↦
(𝑥 + 1)), 𝐴) ↾ ω) = (ω ∩ dom
rec((𝑥 ∈ V ↦
(𝑥 + 1)), 𝐴)) | 
| 19 |  | omex 9684 | . . . . . . . . 9
⊢ ω
∈ V | 
| 20 | 19 | inex1 5316 | . . . . . . . 8
⊢ (ω
∩ dom rec((𝑥 ∈ V
↦ (𝑥 + 1)), 𝐴)) ∈ V | 
| 21 | 18, 20 | eqeltri 2836 | . . . . . . 7
⊢ dom
(rec((𝑥 ∈ V ↦
(𝑥 + 1)), 𝐴) ↾ ω) ∈ V | 
| 22 |  | cnvimass 6099 | . . . . . . 7
⊢ (◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) “ 𝑦) ⊆ dom (rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) | 
| 23 | 21, 22 | ssexi 5321 | . . . . . 6
⊢ (◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) “ 𝑦) ∈ V | 
| 24 | 23 | ax-gen 1794 | . . . . 5
⊢
∀𝑦(◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) “ 𝑦) ∈ V | 
| 25 |  | isowe2 7371 | . . . . 5
⊢ ((◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) Isom < , E
((ℤ≥‘𝐴), ω) ∧ ∀𝑦(◡(rec((𝑥 ∈ V ↦ (𝑥 + 1)), 𝐴) ↾ ω) “ 𝑦) ∈ V) → ( E We
ω → < We (ℤ≥‘𝐴))) | 
| 26 | 17, 24, 25 | sylancl 586 | . . . 4
⊢ (𝐴 ∈ ℤ → ( E We
ω → < We (ℤ≥‘𝐴))) | 
| 27 | 3, 26 | mpi 20 | . . 3
⊢ (𝐴 ∈ ℤ → < We
(ℤ≥‘𝐴)) | 
| 28 |  | uzf 12882 | . . . 4
⊢
ℤ≥:ℤ⟶𝒫 ℤ | 
| 29 | 28 | fdmi 6746 | . . 3
⊢ dom
ℤ≥ = ℤ | 
| 30 | 27, 29 | eleq2s 2858 | . 2
⊢ (𝐴 ∈ dom
ℤ≥ → < We (ℤ≥‘𝐴)) | 
| 31 |  | we0 5679 | . . 3
⊢  < We
∅ | 
| 32 |  | ndmfv 6940 | . . . 4
⊢ (¬
𝐴 ∈ dom
ℤ≥ → (ℤ≥‘𝐴) = ∅) | 
| 33 |  | weeq2 5672 | . . . 4
⊢
((ℤ≥‘𝐴) = ∅ → ( < We
(ℤ≥‘𝐴) ↔ < We ∅)) | 
| 34 | 32, 33 | syl 17 | . . 3
⊢ (¬
𝐴 ∈ dom
ℤ≥ → ( < We (ℤ≥‘𝐴) ↔ < We
∅)) | 
| 35 | 31, 34 | mpbiri 258 | . 2
⊢ (¬
𝐴 ∈ dom
ℤ≥ → < We (ℤ≥‘𝐴)) | 
| 36 | 30, 35 | pm2.61i 182 | 1
⊢  < We
(ℤ≥‘𝐴) |