Metamath Proof Explorer


Theorem eliooord

Description: Ordering implied by a member of an open interval of reals. (Contributed by NM, 17-Aug-2008) (Revised by Mario Carneiro, 9-May-2014)

Ref Expression
Assertion eliooord ⊢ A ∈ B C → B < A ∧ A < C

Proof

Step Hyp Ref Expression
1 eliooxr ⊢ A ∈ B C → B ∈ ℝ * ∧ C ∈ ℝ *
2 elioo2 ⊢ B ∈ ℝ * ∧ C ∈ ℝ * → A ∈ B C ↔ A ∈ ℝ ∧ B < A ∧ A < C
3 1 2 syl ⊢ A ∈ B C → A ∈ B C ↔ A ∈ ℝ ∧ B < A ∧ A < C
4 3 ibi ⊢ A ∈ B C → A ∈ ℝ ∧ B < A ∧ A < C
5 3simpc ⊢ A ∈ ℝ ∧ B < A ∧ A < C → B < A ∧ A < C
6 4 5 syl ⊢ A ∈ B C → B < A ∧ A < C