| Step | Hyp | Ref
| Expression |
| 1 | | 19.26 1870 |
. . 3
⊢
(∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) ↔ (∀𝑥 𝑥 = 𝑧 ∧ ∀𝑥 𝑥 = 𝑤)) |
| 2 | | equid 2011 |
. . . . . . . 8
⊢ 𝑥 = 𝑥 |
| 3 | 2 | a1i 11 |
. . . . . . 7
⊢ (𝑥 = 𝑦 → 𝑥 = 𝑥) |
| 4 | 3 | ax-gen 1795 |
. . . . . 6
⊢
∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑥) |
| 5 | 4 | a1i 11 |
. . . . 5
⊢ (𝑥 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑥)) |
| 6 | | equequ1 2024 |
. . . . . . . . 9
⊢ (𝑥 = 𝑧 → (𝑥 = 𝑥 ↔ 𝑧 = 𝑥)) |
| 7 | | equequ2 2025 |
. . . . . . . . 9
⊢ (𝑥 = 𝑤 → (𝑧 = 𝑥 ↔ 𝑧 = 𝑤)) |
| 8 | 6, 7 | sylan9bb 509 |
. . . . . . . 8
⊢ ((𝑥 = 𝑧 ∧ 𝑥 = 𝑤) → (𝑥 = 𝑥 ↔ 𝑧 = 𝑤)) |
| 9 | 8 | sps-o 38909 |
. . . . . . 7
⊢
(∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) → (𝑥 = 𝑥 ↔ 𝑧 = 𝑤)) |
| 10 | | nfa1-o 38916 |
. . . . . . . 8
⊢
Ⅎ𝑥∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) |
| 11 | 9 | imbi2d 340 |
. . . . . . . 8
⊢
(∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) → ((𝑥 = 𝑦 → 𝑥 = 𝑥) ↔ (𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 12 | 10, 11 | albid 2222 |
. . . . . . 7
⊢
(∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) → (∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑥) ↔ ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 13 | 9, 12 | imbi12d 344 |
. . . . . 6
⊢
(∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) → ((𝑥 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑥)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 14 | 13 | adantr 480 |
. . . . 5
⊢
((∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → ((𝑥 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑥)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 15 | 5, 14 | mpbii 233 |
. . . 4
⊢
((∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 16 | 15 | exp32 420 |
. . 3
⊢
(∀𝑥(𝑥 = 𝑧 ∧ 𝑥 = 𝑤) → (¬ ∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 17 | 1, 16 | sylbir 235 |
. 2
⊢
((∀𝑥 𝑥 = 𝑧 ∧ ∀𝑥 𝑥 = 𝑤) → (¬ ∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 18 | | equequ1 2024 |
. . . . . . 7
⊢ (𝑥 = 𝑦 → (𝑥 = 𝑤 ↔ 𝑦 = 𝑤)) |
| 19 | 18 | ad2antll 729 |
. . . . . 6
⊢ ((¬
∀𝑥 𝑥 = 𝑤 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑥 = 𝑤 ↔ 𝑦 = 𝑤)) |
| 20 | | axc9 2387 |
. . . . . . . . 9
⊢ (¬
∀𝑥 𝑥 = 𝑦 → (¬ ∀𝑥 𝑥 = 𝑤 → (𝑦 = 𝑤 → ∀𝑥 𝑦 = 𝑤))) |
| 21 | 20 | impcom 407 |
. . . . . . . 8
⊢ ((¬
∀𝑥 𝑥 = 𝑤 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → (𝑦 = 𝑤 → ∀𝑥 𝑦 = 𝑤)) |
| 22 | 21 | adantrr 717 |
. . . . . . 7
⊢ ((¬
∀𝑥 𝑥 = 𝑤 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑦 = 𝑤 → ∀𝑥 𝑦 = 𝑤)) |
| 23 | | equtrr 2021 |
. . . . . . . 8
⊢ (𝑦 = 𝑤 → (𝑥 = 𝑦 → 𝑥 = 𝑤)) |
| 24 | 23 | alimi 1811 |
. . . . . . 7
⊢
(∀𝑥 𝑦 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤)) |
| 25 | 22, 24 | syl6 35 |
. . . . . 6
⊢ ((¬
∀𝑥 𝑥 = 𝑤 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑦 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤))) |
| 26 | 19, 25 | sylbid 240 |
. . . . 5
⊢ ((¬
∀𝑥 𝑥 = 𝑤 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑥 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤))) |
| 27 | 26 | adantll 714 |
. . . 4
⊢
(((∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑥 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤))) |
| 28 | | equequ1 2024 |
. . . . . . 7
⊢ (𝑥 = 𝑧 → (𝑥 = 𝑤 ↔ 𝑧 = 𝑤)) |
| 29 | 28 | sps-o 38909 |
. . . . . 6
⊢
(∀𝑥 𝑥 = 𝑧 → (𝑥 = 𝑤 ↔ 𝑧 = 𝑤)) |
| 30 | 29 | imbi2d 340 |
. . . . . . 7
⊢
(∀𝑥 𝑥 = 𝑧 → ((𝑥 = 𝑦 → 𝑥 = 𝑤) ↔ (𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 31 | 30 | dral2-o 38931 |
. . . . . 6
⊢
(∀𝑥 𝑥 = 𝑧 → (∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤) ↔ ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 32 | 29, 31 | imbi12d 344 |
. . . . 5
⊢
(∀𝑥 𝑥 = 𝑧 → ((𝑥 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 33 | 32 | ad2antrr 726 |
. . . 4
⊢
(((∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → ((𝑥 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑤)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 34 | 27, 33 | mpbid 232 |
. . 3
⊢
(((∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 35 | 34 | exp32 420 |
. 2
⊢
((∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (¬ ∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 36 | | equequ2 2025 |
. . . . . . 7
⊢ (𝑥 = 𝑦 → (𝑧 = 𝑥 ↔ 𝑧 = 𝑦)) |
| 37 | 36 | ad2antll 729 |
. . . . . 6
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑥 ↔ 𝑧 = 𝑦)) |
| 38 | | axc9 2387 |
. . . . . . . . 9
⊢ (¬
∀𝑥 𝑥 = 𝑧 → (¬ ∀𝑥 𝑥 = 𝑦 → (𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦))) |
| 39 | 38 | imp 406 |
. . . . . . . 8
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → (𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) |
| 40 | 39 | adantrr 717 |
. . . . . . 7
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑦 → ∀𝑥 𝑧 = 𝑦)) |
| 41 | 36 | biimprcd 250 |
. . . . . . . 8
⊢ (𝑧 = 𝑦 → (𝑥 = 𝑦 → 𝑧 = 𝑥)) |
| 42 | 41 | alimi 1811 |
. . . . . . 7
⊢
(∀𝑥 𝑧 = 𝑦 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥)) |
| 43 | 40, 42 | syl6 35 |
. . . . . 6
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑦 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥))) |
| 44 | 37, 43 | sylbid 240 |
. . . . 5
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥))) |
| 45 | 44 | adantlr 715 |
. . . 4
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ∀𝑥 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥))) |
| 46 | 7 | sps-o 38909 |
. . . . . 6
⊢
(∀𝑥 𝑥 = 𝑤 → (𝑧 = 𝑥 ↔ 𝑧 = 𝑤)) |
| 47 | 46 | imbi2d 340 |
. . . . . . 7
⊢
(∀𝑥 𝑥 = 𝑤 → ((𝑥 = 𝑦 → 𝑧 = 𝑥) ↔ (𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 48 | 47 | dral2-o 38931 |
. . . . . 6
⊢
(∀𝑥 𝑥 = 𝑤 → (∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥) ↔ ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 49 | 46, 48 | imbi12d 344 |
. . . . 5
⊢
(∀𝑥 𝑥 = 𝑤 → ((𝑧 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 50 | 49 | ad2antlr 727 |
. . . 4
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ∀𝑥 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → ((𝑧 = 𝑥 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑥)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 51 | 45, 50 | mpbid 232 |
. . 3
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ∀𝑥 𝑥 = 𝑤) ∧ (¬ ∀𝑥 𝑥 = 𝑦 ∧ 𝑥 = 𝑦)) → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 52 | 51 | exp32 420 |
. 2
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ∀𝑥 𝑥 = 𝑤) → (¬ ∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 53 | | ax6ev 1969 |
. . . . 5
⊢
∃𝑢 𝑢 = 𝑤 |
| 54 | | ax6ev 1969 |
. . . . . . 7
⊢
∃𝑣 𝑣 = 𝑧 |
| 55 | | ax-1 6 |
. . . . . . . . . . 11
⊢ (𝑣 = 𝑢 → (𝑥 = 𝑦 → 𝑣 = 𝑢)) |
| 56 | 55 | alrimiv 1927 |
. . . . . . . . . 10
⊢ (𝑣 = 𝑢 → ∀𝑥(𝑥 = 𝑦 → 𝑣 = 𝑢)) |
| 57 | | equequ1 2024 |
. . . . . . . . . . . . 13
⊢ (𝑣 = 𝑧 → (𝑣 = 𝑢 ↔ 𝑧 = 𝑢)) |
| 58 | | equequ2 2025 |
. . . . . . . . . . . . 13
⊢ (𝑢 = 𝑤 → (𝑧 = 𝑢 ↔ 𝑧 = 𝑤)) |
| 59 | 57, 58 | sylan9bb 509 |
. . . . . . . . . . . 12
⊢ ((𝑣 = 𝑧 ∧ 𝑢 = 𝑤) → (𝑣 = 𝑢 ↔ 𝑧 = 𝑤)) |
| 60 | 59 | adantl 481 |
. . . . . . . . . . 11
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) → (𝑣 = 𝑢 ↔ 𝑧 = 𝑤)) |
| 61 | | dveeq2-o 38934 |
. . . . . . . . . . . . . . 15
⊢ (¬
∀𝑥 𝑥 = 𝑧 → (𝑣 = 𝑧 → ∀𝑥 𝑣 = 𝑧)) |
| 62 | | dveeq2-o 38934 |
. . . . . . . . . . . . . . 15
⊢ (¬
∀𝑥 𝑥 = 𝑤 → (𝑢 = 𝑤 → ∀𝑥 𝑢 = 𝑤)) |
| 63 | 61, 62 | im2anan9 620 |
. . . . . . . . . . . . . 14
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → ((𝑣 = 𝑧 ∧ 𝑢 = 𝑤) → (∀𝑥 𝑣 = 𝑧 ∧ ∀𝑥 𝑢 = 𝑤))) |
| 64 | 63 | imp 406 |
. . . . . . . . . . . . 13
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) → (∀𝑥 𝑣 = 𝑧 ∧ ∀𝑥 𝑢 = 𝑤)) |
| 65 | | 19.26 1870 |
. . . . . . . . . . . . 13
⊢
(∀𝑥(𝑣 = 𝑧 ∧ 𝑢 = 𝑤) ↔ (∀𝑥 𝑣 = 𝑧 ∧ ∀𝑥 𝑢 = 𝑤)) |
| 66 | 64, 65 | sylibr 234 |
. . . . . . . . . . . 12
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) → ∀𝑥(𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) |
| 67 | | nfa1-o 38916 |
. . . . . . . . . . . . 13
⊢
Ⅎ𝑥∀𝑥(𝑣 = 𝑧 ∧ 𝑢 = 𝑤) |
| 68 | 59 | sps-o 38909 |
. . . . . . . . . . . . . 14
⊢
(∀𝑥(𝑣 = 𝑧 ∧ 𝑢 = 𝑤) → (𝑣 = 𝑢 ↔ 𝑧 = 𝑤)) |
| 69 | 68 | imbi2d 340 |
. . . . . . . . . . . . 13
⊢
(∀𝑥(𝑣 = 𝑧 ∧ 𝑢 = 𝑤) → ((𝑥 = 𝑦 → 𝑣 = 𝑢) ↔ (𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 70 | 67, 69 | albid 2222 |
. . . . . . . . . . . 12
⊢
(∀𝑥(𝑣 = 𝑧 ∧ 𝑢 = 𝑤) → (∀𝑥(𝑥 = 𝑦 → 𝑣 = 𝑢) ↔ ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 71 | 66, 70 | syl 17 |
. . . . . . . . . . 11
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) → (∀𝑥(𝑥 = 𝑦 → 𝑣 = 𝑢) ↔ ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 72 | 60, 71 | imbi12d 344 |
. . . . . . . . . 10
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) → ((𝑣 = 𝑢 → ∀𝑥(𝑥 = 𝑦 → 𝑣 = 𝑢)) ↔ (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 73 | 56, 72 | mpbii 233 |
. . . . . . . . 9
⊢ (((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) ∧ (𝑣 = 𝑧 ∧ 𝑢 = 𝑤)) → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 74 | 73 | exp32 420 |
. . . . . . . 8
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (𝑣 = 𝑧 → (𝑢 = 𝑤 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 75 | 74 | exlimdv 1933 |
. . . . . . 7
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (∃𝑣 𝑣 = 𝑧 → (𝑢 = 𝑤 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 76 | 54, 75 | mpi 20 |
. . . . . 6
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (𝑢 = 𝑤 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 77 | 76 | exlimdv 1933 |
. . . . 5
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (∃𝑢 𝑢 = 𝑤 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 78 | 53, 77 | mpi 20 |
. . . 4
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))) |
| 79 | 78 | a1d 25 |
. . 3
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |
| 80 | 79 | a1d 25 |
. 2
⊢ ((¬
∀𝑥 𝑥 = 𝑧 ∧ ¬ ∀𝑥 𝑥 = 𝑤) → (¬ ∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤))))) |
| 81 | 17, 35, 52, 80 | 4cases 1041 |
1
⊢ (¬
∀𝑥 𝑥 = 𝑦 → (𝑥 = 𝑦 → (𝑧 = 𝑤 → ∀𝑥(𝑥 = 𝑦 → 𝑧 = 𝑤)))) |