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Metamath Proof Explorer

Theorem elico1

Description: Membership in a closed-below, open-above interval of extended reals. (Contributed by NM, 24-Dec-2006) (Revised by Mario Carneiro, 3-Nov-2013)

		Ref	Expression
	Assertion	elico1	$⊢ (A \in ℝ^{} \land B \in ℝ^{}) \to (C \in [A, B) \leftrightarrow (C \in ℝ^{*} \land A \leq C \land C < B))$

Proof

Step	Hyp	Ref	Expression
1		df-ico	$⊢ [.) = (x \in ℝ^{}, y \in ℝ^{} ⟼ \{z \in ℝ^{*} \| (x \leq z \land z < y)\})$
2	1	elixx1	$⊢ (A \in ℝ^{} \land B \in ℝ^{}) \to (C \in [A, B) \leftrightarrow (C \in ℝ^{*} \land A \leq C \land C < B))$