Theorem iooex

Description: The set of open intervals of extended reals exists. (Contributed by NM, 6-Feb-2007) (Revised by Mario Carneiro, 3-Nov-2013)

	Ref	Expression
Assertion	iooex	⊢ (,) ∈ V

Proof

Step	Hyp	Ref	Expression
1		df-ioo	⊢ (,) = ( 𝑥 ∈ ℝ* , 𝑦 ∈ ℝ* ↦ { 𝑧 ∈ ℝ* ∣ ( 𝑥 < 𝑧 ∧ 𝑧 < 𝑦 ) } )
2	1	ixxex	⊢ (,) ∈ V