| Step | Hyp | Ref
| Expression |
| 1 | | ax6ev 1969 |
. 2
⊢
∃𝑢 𝑢 = 𝑦 |
| 2 | | ax6ev 1969 |
. 2
⊢
∃𝑣 𝑣 = 𝑤 |
| 3 | | wl-sbcom2d.2 |
. . . . . . . 8
⊢ (𝜑 → ¬ ∀𝑥 𝑥 = 𝑧) |
| 4 | | wl-sbcom2d-lem2 37561 |
. . . . . . . . . . 11
⊢ (¬
∀𝑧 𝑧 = 𝑥 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ ∀𝑥∀𝑧((𝑥 = 𝑢 ∧ 𝑧 = 𝑣) → 𝜓))) |
| 5 | | alcom 2159 |
. . . . . . . . . . . 12
⊢
(∀𝑥∀𝑧((𝑥 = 𝑢 ∧ 𝑧 = 𝑣) → 𝜓) ↔ ∀𝑧∀𝑥((𝑥 = 𝑢 ∧ 𝑧 = 𝑣) → 𝜓)) |
| 6 | | ancomst 464 |
. . . . . . . . . . . . 13
⊢ (((𝑥 = 𝑢 ∧ 𝑧 = 𝑣) → 𝜓) ↔ ((𝑧 = 𝑣 ∧ 𝑥 = 𝑢) → 𝜓)) |
| 7 | 6 | 2albii 1820 |
. . . . . . . . . . . 12
⊢
(∀𝑧∀𝑥((𝑥 = 𝑢 ∧ 𝑧 = 𝑣) → 𝜓) ↔ ∀𝑧∀𝑥((𝑧 = 𝑣 ∧ 𝑥 = 𝑢) → 𝜓)) |
| 8 | 5, 7 | bitri 275 |
. . . . . . . . . . 11
⊢
(∀𝑥∀𝑧((𝑥 = 𝑢 ∧ 𝑧 = 𝑣) → 𝜓) ↔ ∀𝑧∀𝑥((𝑧 = 𝑣 ∧ 𝑥 = 𝑢) → 𝜓)) |
| 9 | 4, 8 | bitrdi 287 |
. . . . . . . . . 10
⊢ (¬
∀𝑧 𝑧 = 𝑥 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ ∀𝑧∀𝑥((𝑧 = 𝑣 ∧ 𝑥 = 𝑢) → 𝜓))) |
| 10 | 9 | naecoms 2434 |
. . . . . . . . 9
⊢ (¬
∀𝑥 𝑥 = 𝑧 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ ∀𝑧∀𝑥((𝑧 = 𝑣 ∧ 𝑥 = 𝑢) → 𝜓))) |
| 11 | | wl-sbcom2d-lem2 37561 |
. . . . . . . . 9
⊢ (¬
∀𝑥 𝑥 = 𝑧 → ([𝑣 / 𝑧][𝑢 / 𝑥]𝜓 ↔ ∀𝑧∀𝑥((𝑧 = 𝑣 ∧ 𝑥 = 𝑢) → 𝜓))) |
| 12 | 10, 11 | bitr4d 282 |
. . . . . . . 8
⊢ (¬
∀𝑥 𝑥 = 𝑧 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ [𝑣 / 𝑧][𝑢 / 𝑥]𝜓)) |
| 13 | 3, 12 | syl 17 |
. . . . . . 7
⊢ (𝜑 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ [𝑣 / 𝑧][𝑢 / 𝑥]𝜓)) |
| 14 | 13 | adantl 481 |
. . . . . 6
⊢ (((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) ∧ 𝜑) → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ [𝑣 / 𝑧][𝑢 / 𝑥]𝜓)) |
| 15 | | wl-sbcom2d.1 |
. . . . . . . 8
⊢ (𝜑 → ¬ ∀𝑥 𝑥 = 𝑤) |
| 16 | | wl-sbcom2d-lem1 37560 |
. . . . . . . 8
⊢ ((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) → (¬ ∀𝑥 𝑥 = 𝑤 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓))) |
| 17 | 15, 16 | syl5 34 |
. . . . . . 7
⊢ ((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) → (𝜑 → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓))) |
| 18 | 17 | imp 406 |
. . . . . 6
⊢ (((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) ∧ 𝜑) → ([𝑢 / 𝑥][𝑣 / 𝑧]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓)) |
| 19 | | wl-sbcom2d.3 |
. . . . . . . . 9
⊢ (𝜑 → ¬ ∀𝑧 𝑧 = 𝑦) |
| 20 | | wl-sbcom2d-lem1 37560 |
. . . . . . . . 9
⊢ ((𝑣 = 𝑤 ∧ 𝑢 = 𝑦) → (¬ ∀𝑧 𝑧 = 𝑦 → ([𝑣 / 𝑧][𝑢 / 𝑥]𝜓 ↔ [𝑤 / 𝑧][𝑦 / 𝑥]𝜓))) |
| 21 | 19, 20 | syl5 34 |
. . . . . . . 8
⊢ ((𝑣 = 𝑤 ∧ 𝑢 = 𝑦) → (𝜑 → ([𝑣 / 𝑧][𝑢 / 𝑥]𝜓 ↔ [𝑤 / 𝑧][𝑦 / 𝑥]𝜓))) |
| 22 | 21 | ancoms 458 |
. . . . . . 7
⊢ ((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) → (𝜑 → ([𝑣 / 𝑧][𝑢 / 𝑥]𝜓 ↔ [𝑤 / 𝑧][𝑦 / 𝑥]𝜓))) |
| 23 | 22 | imp 406 |
. . . . . 6
⊢ (((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) ∧ 𝜑) → ([𝑣 / 𝑧][𝑢 / 𝑥]𝜓 ↔ [𝑤 / 𝑧][𝑦 / 𝑥]𝜓)) |
| 24 | 14, 18, 23 | 3bitr3rd 310 |
. . . . 5
⊢ (((𝑢 = 𝑦 ∧ 𝑣 = 𝑤) ∧ 𝜑) → ([𝑤 / 𝑧][𝑦 / 𝑥]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓)) |
| 25 | 24 | exp31 419 |
. . . 4
⊢ (𝑢 = 𝑦 → (𝑣 = 𝑤 → (𝜑 → ([𝑤 / 𝑧][𝑦 / 𝑥]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓)))) |
| 26 | 25 | exlimdv 1933 |
. . 3
⊢ (𝑢 = 𝑦 → (∃𝑣 𝑣 = 𝑤 → (𝜑 → ([𝑤 / 𝑧][𝑦 / 𝑥]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓)))) |
| 27 | 26 | exlimiv 1930 |
. 2
⊢
(∃𝑢 𝑢 = 𝑦 → (∃𝑣 𝑣 = 𝑤 → (𝜑 → ([𝑤 / 𝑧][𝑦 / 𝑥]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓)))) |
| 28 | 1, 2, 27 | mp2 9 |
1
⊢ (𝜑 → ([𝑤 / 𝑧][𝑦 / 𝑥]𝜓 ↔ [𝑦 / 𝑥][𝑤 / 𝑧]𝜓)) |