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| Mirrors > Home > MPE Home > Th. List > elioore | Structured version Visualization version GIF version | ||
| Description: A member of an open interval of reals is a real. (Contributed by NM, 17-Aug-2008.) (Revised by Mario Carneiro, 3-Nov-2013.) |
| Ref | Expression |
|---|---|
| elioore | ⊢ (𝐴 ∈ (𝐵(,)𝐶) → 𝐴 ∈ ℝ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | elioo3g 13417 | . 2 ⊢ (𝐴 ∈ (𝐵(,)𝐶) ↔ ((𝐵 ∈ ℝ* ∧ 𝐶 ∈ ℝ* ∧ 𝐴 ∈ ℝ*) ∧ (𝐵 < 𝐴 ∧ 𝐴 < 𝐶))) | |
| 2 | 3ancomb 1098 | . . 3 ⊢ ((𝐵 ∈ ℝ* ∧ 𝐶 ∈ ℝ* ∧ 𝐴 ∈ ℝ*) ↔ (𝐵 ∈ ℝ* ∧ 𝐴 ∈ ℝ* ∧ 𝐶 ∈ ℝ*)) | |
| 3 | xrre2 13213 | . . 3 ⊢ (((𝐵 ∈ ℝ* ∧ 𝐴 ∈ ℝ* ∧ 𝐶 ∈ ℝ*) ∧ (𝐵 < 𝐴 ∧ 𝐴 < 𝐶)) → 𝐴 ∈ ℝ) | |
| 4 | 2, 3 | sylanb 581 | . 2 ⊢ (((𝐵 ∈ ℝ* ∧ 𝐶 ∈ ℝ* ∧ 𝐴 ∈ ℝ*) ∧ (𝐵 < 𝐴 ∧ 𝐴 < 𝐶)) → 𝐴 ∈ ℝ) |
| 5 | 1, 4 | sylbi 217 | 1 ⊢ (𝐴 ∈ (𝐵(,)𝐶) → 𝐴 ∈ ℝ) |
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