# Definition:Real Interval/Singleton

## Definition

Let $a, b \in \R$.

Consider the closed interval $\closedint a b \subseteq \R$.

When $a = b$:

$\closedint a b = \closedint a a = \set {x \in \R: a \le x \le a} = \set a$

Such an interval is sometimes referred to as a singleton interval.