# Closed Subset of Real Numbers with Lower Bound contains Infimum

## Theorem

Consider the real number line as a metric space under the usual metric.

Let $A \subseteq \R$ such that $A$ is closed in $\R$ and $A \neq \varnothing$.

Let $A$ be bounded below.

Then $A$ contains its infimum.

## Proof

$\map \inf A \in \map \cl A$
$A = \map \cl A$

Therefore $\map \inf A \in A$.

$\blacksquare$