| Step | Hyp | Ref
| Expression |
| 1 | | eqid 2736 |
. . . . 5
⊢ ∪ 𝐽 =
∪ 𝐽 |
| 2 | 1 | ist0 23263 |
. . . 4
⊢ (𝐽 ∈ Kol2 ↔ (𝐽 ∈ Top ∧ ∀𝑥 ∈ ∪ 𝐽∀𝑦 ∈ ∪ 𝐽(∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) → 𝑥 = 𝑦))) |
| 3 | 2 | simplbi 497 |
. . 3
⊢ (𝐽 ∈ Kol2 → 𝐽 ∈ Top) |
| 4 | 3 | adantl 481 |
. 2
⊢ ((𝜑 ∧ 𝐽 ∈ Kol2) → 𝐽 ∈ Top) |
| 5 | 2 | baib 535 |
. . . 4
⊢ (𝐽 ∈ Top → (𝐽 ∈ Kol2 ↔
∀𝑥 ∈ ∪ 𝐽∀𝑦 ∈ ∪ 𝐽(∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) → 𝑥 = 𝑦))) |
| 6 | 5 | adantl 481 |
. . 3
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (𝐽 ∈ Kol2 ↔ ∀𝑥 ∈ ∪ 𝐽∀𝑦 ∈ ∪ 𝐽(∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) → 𝑥 = 𝑦))) |
| 7 | | ist0cls.1 |
. . . . . 6
⊢ (𝜑 → 𝐵 = ∪ 𝐽) |
| 8 | 7 | adantr 480 |
. . . . 5
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → 𝐵 = ∪ 𝐽) |
| 9 | 8 | eqcomd 2742 |
. . . 4
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → ∪ 𝐽 =
𝐵) |
| 10 | 9 | adantr 480 |
. . . . 5
⊢ (((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽) → ∪ 𝐽 =
𝐵) |
| 11 | | simp-4r 783 |
. . . . . . . . 9
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) → 𝐽 ∈ Top) |
| 12 | | uniexg 7739 |
. . . . . . . . 9
⊢ (𝐽 ∈ Top → ∪ 𝐽
∈ V) |
| 13 | | difexg 5304 |
. . . . . . . . 9
⊢ (∪ 𝐽
∈ V → (∪ 𝐽 ∖ 𝑜) ∈ V) |
| 14 | 11, 12, 13 | 3syl 18 |
. . . . . . . 8
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) → (∪ 𝐽
∖ 𝑜) ∈
V) |
| 15 | 1 | iscld 22970 |
. . . . . . . . . . 11
⊢ (𝐽 ∈ Top → (𝑑 ∈ (Clsd‘𝐽) ↔ (𝑑 ⊆ ∪ 𝐽 ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽))) |
| 16 | 15 | adantl 481 |
. . . . . . . . . 10
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (𝑑 ∈ (Clsd‘𝐽) ↔ (𝑑 ⊆ ∪ 𝐽 ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽))) |
| 17 | | ist0cls.2 |
. . . . . . . . . . . 12
⊢ (𝜑 → 𝐷 = (Clsd‘𝐽)) |
| 18 | 17 | eleq2d 2821 |
. . . . . . . . . . 11
⊢ (𝜑 → (𝑑 ∈ 𝐷 ↔ 𝑑 ∈ (Clsd‘𝐽))) |
| 19 | 18 | adantr 480 |
. . . . . . . . . 10
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (𝑑 ∈ 𝐷 ↔ 𝑑 ∈ (Clsd‘𝐽))) |
| 20 | | simpr 484 |
. . . . . . . . . . . . 13
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → 𝑑 = (∪ 𝐽 ∖ 𝑜)) |
| 21 | | difssd 4117 |
. . . . . . . . . . . . 13
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → (∪ 𝐽 ∖ 𝑜) ⊆ ∪ 𝐽) |
| 22 | 20, 21 | eqsstrd 3998 |
. . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → 𝑑 ⊆ ∪ 𝐽) |
| 23 | 22 | r19.29an 3145 |
. . . . . . . . . . 11
⊢ (((𝜑 ∧ 𝐽 ∈ Top) ∧ ∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜)) → 𝑑 ⊆ ∪ 𝐽) |
| 24 | | simpr 484 |
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → 𝑑 = (∪ 𝐽 ∖ 𝑜)) |
| 25 | 24 | difeq2d 4106 |
. . . . . . . . . . . . . 14
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → (∪ 𝐽 ∖ 𝑑) = (∪ 𝐽 ∖ (∪ 𝐽
∖ 𝑜))) |
| 26 | 1 | eltopss 22850 |
. . . . . . . . . . . . . . . . 17
⊢ ((𝐽 ∈ Top ∧ 𝑜 ∈ 𝐽) → 𝑜 ⊆ ∪ 𝐽) |
| 27 | 26 | ad5ant24 760 |
. . . . . . . . . . . . . . . 16
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → 𝑜 ⊆ ∪ 𝐽) |
| 28 | | dfss4 4249 |
. . . . . . . . . . . . . . . 16
⊢ (𝑜 ⊆ ∪ 𝐽
↔ (∪ 𝐽 ∖ (∪ 𝐽 ∖ 𝑜)) = 𝑜) |
| 29 | 27, 28 | sylib 218 |
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → (∪ 𝐽 ∖ (∪ 𝐽
∖ 𝑜)) = 𝑜) |
| 30 | | simplr 768 |
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → 𝑜 ∈ 𝐽) |
| 31 | 29, 30 | eqeltrd 2835 |
. . . . . . . . . . . . . 14
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → (∪ 𝐽 ∖ (∪ 𝐽
∖ 𝑜)) ∈ 𝐽) |
| 32 | 25, 31 | eqeltrd 2835 |
. . . . . . . . . . . . 13
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ 𝑜 ∈ 𝐽) ∧ 𝑑 = (∪ 𝐽 ∖ 𝑜)) → (∪ 𝐽 ∖ 𝑑) ∈ 𝐽) |
| 33 | 32 | r19.29an 3145 |
. . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) ∧ ∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜)) → (∪ 𝐽 ∖ 𝑑) ∈ 𝐽) |
| 34 | | simpr 484 |
. . . . . . . . . . . . 13
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽) → (∪ 𝐽
∖ 𝑑) ∈ 𝐽) |
| 35 | | simpr 484 |
. . . . . . . . . . . . . . 15
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ (∪ 𝐽 ∖ 𝑑) ∈ 𝐽) ∧ 𝑜 = (∪ 𝐽 ∖ 𝑑)) → 𝑜 = (∪ 𝐽 ∖ 𝑑)) |
| 36 | 35 | difeq2d 4106 |
. . . . . . . . . . . . . 14
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ (∪ 𝐽 ∖ 𝑑) ∈ 𝐽) ∧ 𝑜 = (∪ 𝐽 ∖ 𝑑)) → (∪ 𝐽 ∖ 𝑜) = (∪ 𝐽 ∖ (∪ 𝐽
∖ 𝑑))) |
| 37 | 36 | eqeq2d 2747 |
. . . . . . . . . . . . 13
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽)
∧ (∪ 𝐽 ∖ 𝑑) ∈ 𝐽) ∧ 𝑜 = (∪ 𝐽 ∖ 𝑑)) → (𝑑 = (∪ 𝐽 ∖ 𝑜) ↔ 𝑑 = (∪ 𝐽 ∖ (∪ 𝐽
∖ 𝑑)))) |
| 38 | | simplr 768 |
. . . . . . . . . . . . . . 15
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽) → 𝑑 ⊆ ∪ 𝐽) |
| 39 | | dfss4 4249 |
. . . . . . . . . . . . . . 15
⊢ (𝑑 ⊆ ∪ 𝐽
↔ (∪ 𝐽 ∖ (∪ 𝐽 ∖ 𝑑)) = 𝑑) |
| 40 | 38, 39 | sylib 218 |
. . . . . . . . . . . . . 14
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽) → (∪ 𝐽
∖ (∪ 𝐽 ∖ 𝑑)) = 𝑑) |
| 41 | 40 | eqcomd 2742 |
. . . . . . . . . . . . 13
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽) → 𝑑 = (∪ 𝐽 ∖ (∪ 𝐽
∖ 𝑑))) |
| 42 | 34, 37, 41 | rspcedvd 3608 |
. . . . . . . . . . . 12
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽) → ∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜)) |
| 43 | 33, 42 | impbida 800 |
. . . . . . . . . . 11
⊢ (((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑑 ⊆ ∪ 𝐽) → (∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜) ↔ (∪ 𝐽 ∖ 𝑑) ∈ 𝐽)) |
| 44 | 23, 43 | biadanid 822 |
. . . . . . . . . 10
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜) ↔ (𝑑 ⊆ ∪ 𝐽 ∧ (∪ 𝐽
∖ 𝑑) ∈ 𝐽))) |
| 45 | 16, 19, 44 | 3bitr4d 311 |
. . . . . . . . 9
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (𝑑 ∈ 𝐷 ↔ ∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜))) |
| 46 | 45 | ad2antrr 726 |
. . . . . . . 8
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽) ∧ 𝑦 ∈ ∪ 𝐽) → (𝑑 ∈ 𝐷 ↔ ∃𝑜 ∈ 𝐽 𝑑 = (∪ 𝐽 ∖ 𝑜))) |
| 47 | | simpr 484 |
. . . . . . . . . . . 12
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → 𝑑 = (∪
𝐽 ∖ 𝑜)) |
| 48 | 47 | eleq2d 2821 |
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → (𝑥 ∈ 𝑑 ↔ 𝑥 ∈ (∪ 𝐽 ∖ 𝑜))) |
| 49 | | eldif 3941 |
. . . . . . . . . . . . 13
⊢ (𝑥 ∈ (∪ 𝐽
∖ 𝑜) ↔ (𝑥 ∈ ∪ 𝐽
∧ ¬ 𝑥 ∈ 𝑜)) |
| 50 | 49 | baib 535 |
. . . . . . . . . . . 12
⊢ (𝑥 ∈ ∪ 𝐽
→ (𝑥 ∈ (∪ 𝐽
∖ 𝑜) ↔ ¬
𝑥 ∈ 𝑜)) |
| 51 | 50 | ad3antlr 731 |
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → (𝑥 ∈ (∪ 𝐽
∖ 𝑜) ↔ ¬
𝑥 ∈ 𝑜)) |
| 52 | 48, 51 | bitrd 279 |
. . . . . . . . . 10
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → (𝑥 ∈ 𝑑 ↔ ¬ 𝑥 ∈ 𝑜)) |
| 53 | 47 | eleq2d 2821 |
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → (𝑦 ∈ 𝑑 ↔ 𝑦 ∈ (∪ 𝐽 ∖ 𝑜))) |
| 54 | | eldif 3941 |
. . . . . . . . . . . . 13
⊢ (𝑦 ∈ (∪ 𝐽
∖ 𝑜) ↔ (𝑦 ∈ ∪ 𝐽
∧ ¬ 𝑦 ∈ 𝑜)) |
| 55 | 54 | baib 535 |
. . . . . . . . . . . 12
⊢ (𝑦 ∈ ∪ 𝐽
→ (𝑦 ∈ (∪ 𝐽
∖ 𝑜) ↔ ¬
𝑦 ∈ 𝑜)) |
| 56 | 55 | ad2antlr 727 |
. . . . . . . . . . 11
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → (𝑦 ∈ (∪ 𝐽
∖ 𝑜) ↔ ¬
𝑦 ∈ 𝑜)) |
| 57 | 53, 56 | bitrd 279 |
. . . . . . . . . 10
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → (𝑦 ∈ 𝑑 ↔ ¬ 𝑦 ∈ 𝑜)) |
| 58 | 52, 57 | bibi12d 345 |
. . . . . . . . 9
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → ((𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) ↔ (¬ 𝑥 ∈ 𝑜 ↔ ¬ 𝑦 ∈ 𝑜))) |
| 59 | | notbi 319 |
. . . . . . . . 9
⊢ ((𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) ↔ (¬ 𝑥 ∈ 𝑜 ↔ ¬ 𝑦 ∈ 𝑜)) |
| 60 | 58, 59 | bitr4di 289 |
. . . . . . . 8
⊢
(((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽)
∧ 𝑦 ∈ ∪ 𝐽)
∧ 𝑑 = (∪ 𝐽
∖ 𝑜)) → ((𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) ↔ (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜))) |
| 61 | 14, 46, 60 | ralxfr2d 5385 |
. . . . . . 7
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽) ∧ 𝑦 ∈ ∪ 𝐽) → (∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) ↔ ∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜))) |
| 62 | 61 | bicomd 223 |
. . . . . 6
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽) ∧ 𝑦 ∈ ∪ 𝐽) → (∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) ↔ ∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑))) |
| 63 | 62 | imbi1d 341 |
. . . . 5
⊢ ((((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽) ∧ 𝑦 ∈ ∪ 𝐽) → ((∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) → 𝑥 = 𝑦) ↔ (∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) → 𝑥 = 𝑦))) |
| 64 | 10, 63 | raleqbidva 3315 |
. . . 4
⊢ (((𝜑 ∧ 𝐽 ∈ Top) ∧ 𝑥 ∈ ∪ 𝐽) → (∀𝑦 ∈ ∪ 𝐽(∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) → 𝑥 = 𝑦) ↔ ∀𝑦 ∈ 𝐵 (∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) → 𝑥 = 𝑦))) |
| 65 | 9, 64 | raleqbidva 3315 |
. . 3
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (∀𝑥 ∈ ∪ 𝐽∀𝑦 ∈ ∪ 𝐽(∀𝑜 ∈ 𝐽 (𝑥 ∈ 𝑜 ↔ 𝑦 ∈ 𝑜) → 𝑥 = 𝑦) ↔ ∀𝑥 ∈ 𝐵 ∀𝑦 ∈ 𝐵 (∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) → 𝑥 = 𝑦))) |
| 66 | 6, 65 | bitrd 279 |
. 2
⊢ ((𝜑 ∧ 𝐽 ∈ Top) → (𝐽 ∈ Kol2 ↔ ∀𝑥 ∈ 𝐵 ∀𝑦 ∈ 𝐵 (∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) → 𝑥 = 𝑦))) |
| 67 | 4, 66 | biadanid 822 |
1
⊢ (𝜑 → (𝐽 ∈ Kol2 ↔ (𝐽 ∈ Top ∧ ∀𝑥 ∈ 𝐵 ∀𝑦 ∈ 𝐵 (∀𝑑 ∈ 𝐷 (𝑥 ∈ 𝑑 ↔ 𝑦 ∈ 𝑑) → 𝑥 = 𝑦)))) |