suprcl

Description: Closure of supremum of a nonempty bounded set of reals. (Contributed by NM, 12-Oct-2004)

		Ref	Expression
	Assertion	suprcl	$⊢ (A \subseteq ℝ \land A \neq \emptyset \land \exists x \in ℝ \forall y \in A y \leq x) \to sup (A ℝ <) \in ℝ$

Step	Hyp	Ref	Expression
1		ltso	$⊢ < Or ℝ$
2	1	a1i	$⊢ (A \subseteq ℝ \land A \neq \emptyset \land \exists x \in ℝ \forall y \in A y \leq x) \to < Or ℝ$
3		sup3	$⊢ (A \subseteq ℝ \land A \neq \emptyset \land \exists x \in ℝ \forall y \in A y \leq x) \to \exists x \in ℝ (\forall y \in A \neg x < y \land \forall y \in ℝ (y < x \to \exists z \in A y < z))$
4	2 3	supcl	$⊢ (A \subseteq ℝ \land A \neq \emptyset \land \exists x \in ℝ \forall y \in A y \leq x) \to sup (A ℝ <) \in ℝ$

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