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| Mirrors > Home > MPE Home > Th. List > incom | Structured version Visualization version GIF version | ||
| Description: Commutative law for intersection of classes. Exercise 7 of [TakeutiZaring] p. 17. (Contributed by NM, 21-Jun-1993.) |
| Ref | Expression |
|---|---|
| incom | ⊢ (𝐴 ∩ 𝐵) = (𝐵 ∩ 𝐴) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ancom 466 | . . 3 ⊢ ((𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵) ↔ (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)) | |
| 2 | elin 3796 | . . 3 ⊢ (𝑥 ∈ (𝐴 ∩ 𝐵) ↔ (𝑥 ∈ 𝐴 ∧ 𝑥 ∈ 𝐵)) | |
| 3 | elin 3796 | . . 3 ⊢ (𝑥 ∈ (𝐵 ∩ 𝐴) ↔ (𝑥 ∈ 𝐵 ∧ 𝑥 ∈ 𝐴)) | |
| 4 | 1, 2, 3 | 3bitr4i 292 | . 2 ⊢ (𝑥 ∈ (𝐴 ∩ 𝐵) ↔ 𝑥 ∈ (𝐵 ∩ 𝐴)) |
| 5 | 4 | eqriv 2619 | 1 ⊢ (𝐴 ∩ 𝐵) = (𝐵 ∩ 𝐴) |
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