Let $P = (\mathbb{R}, {\leq})$ be the D1102: Ordered set of real numbers such that

(i)	$a, b \in \mathbb{R}$ are each a D993: Real number

The closed real interval from $a$ to $b$ is the D11: Set \begin{equation} [a, b] : = \{ x \in \mathbb{R} : a \leq x, x \leq b \} \end{equation}