| Step | Hyp | Ref
| Expression |
| 1 | | sbcex 3780 |
. 2
⊢
([𝐴 / 𝑥]𝐵𝑅𝐶 → 𝐴 ∈ V) |
| 2 | | br0 5173 |
. . . 4
⊢ ¬
⦋𝐴 / 𝑥⦌𝐵∅⦋𝐴 / 𝑥⦌𝐶 |
| 3 | | csbprc 4389 |
. . . . 5
⊢ (¬
𝐴 ∈ V →
⦋𝐴 / 𝑥⦌𝑅 = ∅) |
| 4 | 3 | breqd 5135 |
. . . 4
⊢ (¬
𝐴 ∈ V →
(⦋𝐴 / 𝑥⦌𝐵⦋𝐴 / 𝑥⦌𝑅⦋𝐴 / 𝑥⦌𝐶 ↔ ⦋𝐴 / 𝑥⦌𝐵∅⦋𝐴 / 𝑥⦌𝐶)) |
| 5 | 2, 4 | mtbiri 327 |
. . 3
⊢ (¬
𝐴 ∈ V → ¬
⦋𝐴 / 𝑥⦌𝐵⦋𝐴 / 𝑥⦌𝑅⦋𝐴 / 𝑥⦌𝐶) |
| 6 | 5 | con4i 114 |
. 2
⊢
(⦋𝐴 /
𝑥⦌𝐵⦋𝐴 / 𝑥⦌𝑅⦋𝐴 / 𝑥⦌𝐶 → 𝐴 ∈ V) |
| 7 | | dfsbcq2 3773 |
. . 3
⊢ (𝑦 = 𝐴 → ([𝑦 / 𝑥]𝐵𝑅𝐶 ↔ [𝐴 / 𝑥]𝐵𝑅𝐶)) |
| 8 | | csbeq1 3882 |
. . . 4
⊢ (𝑦 = 𝐴 → ⦋𝑦 / 𝑥⦌𝐵 = ⦋𝐴 / 𝑥⦌𝐵) |
| 9 | | csbeq1 3882 |
. . . 4
⊢ (𝑦 = 𝐴 → ⦋𝑦 / 𝑥⦌𝑅 = ⦋𝐴 / 𝑥⦌𝑅) |
| 10 | | csbeq1 3882 |
. . . 4
⊢ (𝑦 = 𝐴 → ⦋𝑦 / 𝑥⦌𝐶 = ⦋𝐴 / 𝑥⦌𝐶) |
| 11 | 8, 9, 10 | breq123d 5138 |
. . 3
⊢ (𝑦 = 𝐴 → (⦋𝑦 / 𝑥⦌𝐵⦋𝑦 / 𝑥⦌𝑅⦋𝑦 / 𝑥⦌𝐶 ↔ ⦋𝐴 / 𝑥⦌𝐵⦋𝐴 / 𝑥⦌𝑅⦋𝐴 / 𝑥⦌𝐶)) |
| 12 | | nfcsb1v 3903 |
. . . . 5
⊢
Ⅎ𝑥⦋𝑦 / 𝑥⦌𝐵 |
| 13 | | nfcsb1v 3903 |
. . . . 5
⊢
Ⅎ𝑥⦋𝑦 / 𝑥⦌𝑅 |
| 14 | | nfcsb1v 3903 |
. . . . 5
⊢
Ⅎ𝑥⦋𝑦 / 𝑥⦌𝐶 |
| 15 | 12, 13, 14 | nfbr 5171 |
. . . 4
⊢
Ⅎ𝑥⦋𝑦 / 𝑥⦌𝐵⦋𝑦 / 𝑥⦌𝑅⦋𝑦 / 𝑥⦌𝐶 |
| 16 | | csbeq1a 3893 |
. . . . 5
⊢ (𝑥 = 𝑦 → 𝐵 = ⦋𝑦 / 𝑥⦌𝐵) |
| 17 | | csbeq1a 3893 |
. . . . 5
⊢ (𝑥 = 𝑦 → 𝑅 = ⦋𝑦 / 𝑥⦌𝑅) |
| 18 | | csbeq1a 3893 |
. . . . 5
⊢ (𝑥 = 𝑦 → 𝐶 = ⦋𝑦 / 𝑥⦌𝐶) |
| 19 | 16, 17, 18 | breq123d 5138 |
. . . 4
⊢ (𝑥 = 𝑦 → (𝐵𝑅𝐶 ↔ ⦋𝑦 / 𝑥⦌𝐵⦋𝑦 / 𝑥⦌𝑅⦋𝑦 / 𝑥⦌𝐶)) |
| 20 | 15, 19 | sbiev 2315 |
. . 3
⊢ ([𝑦 / 𝑥]𝐵𝑅𝐶 ↔ ⦋𝑦 / 𝑥⦌𝐵⦋𝑦 / 𝑥⦌𝑅⦋𝑦 / 𝑥⦌𝐶) |
| 21 | 7, 11, 20 | vtoclbg 3541 |
. 2
⊢ (𝐴 ∈ V → ([𝐴 / 𝑥]𝐵𝑅𝐶 ↔ ⦋𝐴 / 𝑥⦌𝐵⦋𝐴 / 𝑥⦌𝑅⦋𝐴 / 𝑥⦌𝐶)) |
| 22 | 1, 6, 21 | pm5.21nii 378 |
1
⊢
([𝐴 / 𝑥]𝐵𝑅𝐶 ↔ ⦋𝐴 / 𝑥⦌𝐵⦋𝐴 / 𝑥⦌𝑅⦋𝐴 / 𝑥⦌𝐶) |