Proof of Theorem bnj919
| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | bnj919.4 | . 2
⊢ (𝜒′ ↔ [𝑃 / 𝑛]𝜒) | 
| 2 |  | bnj919.1 | . . 3
⊢ (𝜒 ↔ (𝑛 ∈ 𝐷 ∧ 𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓)) | 
| 3 | 2 | sbcbii 3846 | . 2
⊢
([𝑃 / 𝑛]𝜒 ↔ [𝑃 / 𝑛](𝑛 ∈ 𝐷 ∧ 𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓)) | 
| 4 |  | bnj919.5 | . . 3
⊢ 𝑃 ∈ V | 
| 5 |  | df-bnj17 34701 | . . . . 5
⊢ ((𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′) ↔ ((𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′) ∧ 𝜓′)) | 
| 6 |  | nfv 1914 | . . . . . . 7
⊢
Ⅎ𝑛 𝑃 ∈ 𝐷 | 
| 7 |  | nfv 1914 | . . . . . . 7
⊢
Ⅎ𝑛 𝐹 Fn 𝑃 | 
| 8 |  | bnj919.2 | . . . . . . . 8
⊢ (𝜑′ ↔ [𝑃 / 𝑛]𝜑) | 
| 9 |  | nfsbc1v 3808 | . . . . . . . 8
⊢
Ⅎ𝑛[𝑃 / 𝑛]𝜑 | 
| 10 | 8, 9 | nfxfr 1853 | . . . . . . 7
⊢
Ⅎ𝑛𝜑′ | 
| 11 | 6, 7, 10 | nf3an 1901 | . . . . . 6
⊢
Ⅎ𝑛(𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′) | 
| 12 |  | bnj919.3 | . . . . . . 7
⊢ (𝜓′ ↔ [𝑃 / 𝑛]𝜓) | 
| 13 |  | nfsbc1v 3808 | . . . . . . 7
⊢
Ⅎ𝑛[𝑃 / 𝑛]𝜓 | 
| 14 | 12, 13 | nfxfr 1853 | . . . . . 6
⊢
Ⅎ𝑛𝜓′ | 
| 15 | 11, 14 | nfan 1899 | . . . . 5
⊢
Ⅎ𝑛((𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′) ∧ 𝜓′) | 
| 16 | 5, 15 | nfxfr 1853 | . . . 4
⊢
Ⅎ𝑛(𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′) | 
| 17 |  | eleq1 2829 | . . . . . 6
⊢ (𝑛 = 𝑃 → (𝑛 ∈ 𝐷 ↔ 𝑃 ∈ 𝐷)) | 
| 18 |  | fneq2 6660 | . . . . . . 7
⊢ (𝑛 = 𝑃 → (𝐹 Fn 𝑛 ↔ 𝐹 Fn 𝑃)) | 
| 19 |  | sbceq1a 3799 | . . . . . . . 8
⊢ (𝑛 = 𝑃 → (𝜑 ↔ [𝑃 / 𝑛]𝜑)) | 
| 20 | 19, 8 | bitr4di 289 | . . . . . . 7
⊢ (𝑛 = 𝑃 → (𝜑 ↔ 𝜑′)) | 
| 21 |  | sbceq1a 3799 | . . . . . . . 8
⊢ (𝑛 = 𝑃 → (𝜓 ↔ [𝑃 / 𝑛]𝜓)) | 
| 22 | 21, 12 | bitr4di 289 | . . . . . . 7
⊢ (𝑛 = 𝑃 → (𝜓 ↔ 𝜓′)) | 
| 23 | 18, 20, 22 | 3anbi123d 1438 | . . . . . 6
⊢ (𝑛 = 𝑃 → ((𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓) ↔ (𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′))) | 
| 24 | 17, 23 | anbi12d 632 | . . . . 5
⊢ (𝑛 = 𝑃 → ((𝑛 ∈ 𝐷 ∧ (𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓)) ↔ (𝑃 ∈ 𝐷 ∧ (𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′)))) | 
| 25 |  | bnj252 34717 | . . . . 5
⊢ ((𝑛 ∈ 𝐷 ∧ 𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓) ↔ (𝑛 ∈ 𝐷 ∧ (𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓))) | 
| 26 |  | bnj252 34717 | . . . . 5
⊢ ((𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′) ↔ (𝑃 ∈ 𝐷 ∧ (𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′))) | 
| 27 | 24, 25, 26 | 3bitr4g 314 | . . . 4
⊢ (𝑛 = 𝑃 → ((𝑛 ∈ 𝐷 ∧ 𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓) ↔ (𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′))) | 
| 28 | 16, 27 | sbciegf 3827 | . . 3
⊢ (𝑃 ∈ V → ([𝑃 / 𝑛](𝑛 ∈ 𝐷 ∧ 𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓) ↔ (𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′))) | 
| 29 | 4, 28 | ax-mp 5 | . 2
⊢
([𝑃 / 𝑛](𝑛 ∈ 𝐷 ∧ 𝐹 Fn 𝑛 ∧ 𝜑 ∧ 𝜓) ↔ (𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′)) | 
| 30 | 1, 3, 29 | 3bitri 297 | 1
⊢ (𝜒′ ↔ (𝑃 ∈ 𝐷 ∧ 𝐹 Fn 𝑃 ∧ 𝜑′ ∧ 𝜓′)) |