Step | Hyp | Ref
| Expression |
1 | | pm2.1 894 |
. . 3
⊢ (¬
{𝐴, 𝐵, 𝐶} = ∅ ∨ {𝐴, 𝐵, 𝐶} = ∅) |
2 | | df-ne 2944 |
. . . . 5
⊢ ({𝐴, 𝐵, 𝐶} ≠ ∅ ↔ ¬ {𝐴, 𝐵, 𝐶} = ∅) |
3 | 2 | bicomi 223 |
. . . 4
⊢ (¬
{𝐴, 𝐵, 𝐶} = ∅ ↔ {𝐴, 𝐵, 𝐶} ≠ ∅) |
4 | 3 | orbi1i 911 |
. . 3
⊢ ((¬
{𝐴, 𝐵, 𝐶} = ∅ ∨ {𝐴, 𝐵, 𝐶} = ∅) ↔ ({𝐴, 𝐵, 𝐶} ≠ ∅ ∨ {𝐴, 𝐵, 𝐶} = ∅)) |
5 | 1, 4 | mpbi 229 |
. 2
⊢ ({𝐴, 𝐵, 𝐶} ≠ ∅ ∨ {𝐴, 𝐵, 𝐶} = ∅) |
6 | | zfregs2 9491 |
. . . 4
⊢ ({𝐴, 𝐵, 𝐶} ≠ ∅ → ¬ ∀𝑥 ∈ {𝐴, 𝐵, 𝐶}∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥)) |
7 | | en3lplem2VD 42464 |
. . . . . . 7
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) → (𝑥 ∈ {𝐴, 𝐵, 𝐶} → ∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥))) |
8 | 7 | alrimiv 1930 |
. . . . . 6
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) → ∀𝑥(𝑥 ∈ {𝐴, 𝐵, 𝐶} → ∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥))) |
9 | | df-ral 3069 |
. . . . . 6
⊢
(∀𝑥 ∈
{𝐴, 𝐵, 𝐶}∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥) ↔ ∀𝑥(𝑥 ∈ {𝐴, 𝐵, 𝐶} → ∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥))) |
10 | 8, 9 | sylibr 233 |
. . . . 5
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) → ∀𝑥 ∈ {𝐴, 𝐵, 𝐶}∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥)) |
11 | 10 | con3i 154 |
. . . 4
⊢ (¬
∀𝑥 ∈ {𝐴, 𝐵, 𝐶}∃𝑦(𝑦 ∈ {𝐴, 𝐵, 𝐶} ∧ 𝑦 ∈ 𝑥) → ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴)) |
12 | 6, 11 | syl 17 |
. . 3
⊢ ({𝐴, 𝐵, 𝐶} ≠ ∅ → ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴)) |
13 | | idn1 42194 |
. . . . . . 7
⊢ ( {𝐴, 𝐵, 𝐶} = ∅ ▶ {𝐴, 𝐵, 𝐶} = ∅ ) |
14 | | noel 4264 |
. . . . . . 7
⊢ ¬
𝐶 ∈
∅ |
15 | | eleq2 2827 |
. . . . . . . . 9
⊢ ({𝐴, 𝐵, 𝐶} = ∅ → (𝐶 ∈ {𝐴, 𝐵, 𝐶} ↔ 𝐶 ∈ ∅)) |
16 | 15 | notbid 318 |
. . . . . . . 8
⊢ ({𝐴, 𝐵, 𝐶} = ∅ → (¬ 𝐶 ∈ {𝐴, 𝐵, 𝐶} ↔ ¬ 𝐶 ∈ ∅)) |
17 | 16 | biimprd 247 |
. . . . . . 7
⊢ ({𝐴, 𝐵, 𝐶} = ∅ → (¬ 𝐶 ∈ ∅ → ¬ 𝐶 ∈ {𝐴, 𝐵, 𝐶})) |
18 | 13, 14, 17 | e10 42314 |
. . . . . 6
⊢ ( {𝐴, 𝐵, 𝐶} = ∅ ▶ ¬
𝐶 ∈ {𝐴, 𝐵, 𝐶} ) |
19 | | tpid3g 4708 |
. . . . . . 7
⊢ (𝐶 ∈ 𝐴 → 𝐶 ∈ {𝐴, 𝐵, 𝐶}) |
20 | 19 | con3i 154 |
. . . . . 6
⊢ (¬
𝐶 ∈ {𝐴, 𝐵, 𝐶} → ¬ 𝐶 ∈ 𝐴) |
21 | 18, 20 | e1a 42247 |
. . . . 5
⊢ ( {𝐴, 𝐵, 𝐶} = ∅ ▶ ¬
𝐶 ∈ 𝐴 ) |
22 | | simp3 1137 |
. . . . . 6
⊢ ((𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) → 𝐶 ∈ 𝐴) |
23 | 22 | con3i 154 |
. . . . 5
⊢ (¬
𝐶 ∈ 𝐴 → ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴)) |
24 | 21, 23 | e1a 42247 |
. . . 4
⊢ ( {𝐴, 𝐵, 𝐶} = ∅ ▶ ¬
(𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) ) |
25 | 24 | in1 42191 |
. . 3
⊢ ({𝐴, 𝐵, 𝐶} = ∅ → ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴)) |
26 | 12, 25 | jaoi 854 |
. 2
⊢ (({𝐴, 𝐵, 𝐶} ≠ ∅ ∨ {𝐴, 𝐵, 𝐶} = ∅) → ¬ (𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴)) |
27 | 5, 26 | ax-mp 5 |
1
⊢ ¬
(𝐴 ∈ 𝐵 ∧ 𝐵 ∈ 𝐶 ∧ 𝐶 ∈ 𝐴) |