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	$$⊢\left(.\right)\in \mathrm{V}$$

Proof

Step	Hyp	Ref	Expression
1		df-ioo	$$⊢\left(.\right)=\left(x\in {ℝ}^{*},y\in {ℝ}^{*}⟼\left\{z\in {ℝ}^{*}|\left(x<z\wedge z<y\right)\right\}\right)$$
2	1	ixxex	$$⊢\left(.\right)\in \mathrm{V}$$