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Mirrors > Home > MPE Home > Th. List > disjeq0 | Structured version Visualization version GIF version |
Description: Two disjoint sets are equal iff both are empty. (Contributed by AV, 19-Jun-2022.) |
Ref | Expression |
---|---|
disjeq0 | ⊢ ((𝐴 ∩ 𝐵) = ∅ → (𝐴 = 𝐵 ↔ (𝐴 = ∅ ∧ 𝐵 = ∅))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ineq1 4131 | . . . . . 6 ⊢ (𝐴 = 𝐵 → (𝐴 ∩ 𝐵) = (𝐵 ∩ 𝐵)) | |
2 | inidm 4145 | . . . . . 6 ⊢ (𝐵 ∩ 𝐵) = 𝐵 | |
3 | 1, 2 | eqtrdi 2849 | . . . . 5 ⊢ (𝐴 = 𝐵 → (𝐴 ∩ 𝐵) = 𝐵) |
4 | 3 | eqeq1d 2800 | . . . 4 ⊢ (𝐴 = 𝐵 → ((𝐴 ∩ 𝐵) = ∅ ↔ 𝐵 = ∅)) |
5 | eqtr 2818 | . . . . . 6 ⊢ ((𝐴 = 𝐵 ∧ 𝐵 = ∅) → 𝐴 = ∅) | |
6 | simpr 488 | . . . . . 6 ⊢ ((𝐴 = 𝐵 ∧ 𝐵 = ∅) → 𝐵 = ∅) | |
7 | 5, 6 | jca 515 | . . . . 5 ⊢ ((𝐴 = 𝐵 ∧ 𝐵 = ∅) → (𝐴 = ∅ ∧ 𝐵 = ∅)) |
8 | 7 | ex 416 | . . . 4 ⊢ (𝐴 = 𝐵 → (𝐵 = ∅ → (𝐴 = ∅ ∧ 𝐵 = ∅))) |
9 | 4, 8 | sylbid 243 | . . 3 ⊢ (𝐴 = 𝐵 → ((𝐴 ∩ 𝐵) = ∅ → (𝐴 = ∅ ∧ 𝐵 = ∅))) |
10 | 9 | com12 32 | . 2 ⊢ ((𝐴 ∩ 𝐵) = ∅ → (𝐴 = 𝐵 → (𝐴 = ∅ ∧ 𝐵 = ∅))) |
11 | eqtr3 2820 | . 2 ⊢ ((𝐴 = ∅ ∧ 𝐵 = ∅) → 𝐴 = 𝐵) | |
12 | 10, 11 | impbid1 228 | 1 ⊢ ((𝐴 ∩ 𝐵) = ∅ → (𝐴 = 𝐵 ↔ (𝐴 = ∅ ∧ 𝐵 = ∅))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 209 ∧ wa 399 = wceq 1538 ∩ cin 3880 ∅c0 4243 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-ext 2770 |
This theorem depends on definitions: df-bi 210 df-an 400 df-ex 1782 df-sb 2070 df-clab 2777 df-cleq 2791 df-clel 2870 df-rab 3115 df-v 3443 df-in 3888 |
This theorem is referenced by: epnsym 9056 |
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