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| Mirrors > Home > ILE Home > Th. List > brel | GIF version | ||
| Description: Two things in a binary relation belong to the relation's domain. (Contributed by NM, 17-May-1996.) (Revised by Mario Carneiro, 26-Apr-2015.) | 
| Ref | Expression | 
|---|---|
| brel.1 | ⊢ 𝑅 ⊆ (𝐶 × 𝐷) | 
| Ref | Expression | 
|---|---|
| brel | ⊢ (𝐴𝑅𝐵 → (𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷)) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | brel.1 | . . 3 ⊢ 𝑅 ⊆ (𝐶 × 𝐷) | |
| 2 | 1 | ssbri 4077 | . 2 ⊢ (𝐴𝑅𝐵 → 𝐴(𝐶 × 𝐷)𝐵) | 
| 3 | brxp 4694 | . 2 ⊢ (𝐴(𝐶 × 𝐷)𝐵 ↔ (𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷)) | |
| 4 | 2, 3 | sylib 122 | 1 ⊢ (𝐴𝑅𝐵 → (𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷)) | 
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