Set of symbols
Alphabet
Deduction system
Theory
Zermelo-Fraenkel set theory
Set
Binary cartesian set product
Binary relation
Binary endorelation
Preordering relation
Partial ordering relation
Partially ordered set
Closed interval
Closed real interval
Open real interval
Formulation 0
Let $P = (\mathbb{R}, {<})$ be the D1101: Strictly ordered set of real numbers such that
(i) $a, b \in \mathbb{R}$ are each a D993: Real number
The open real interval from $a$ to $b$ is the D11: Set \begin{equation} (a, b) : = \{ x \in \mathbb{R} : a < x < b \} \end{equation}
Formulation 1
Let $P = (\mathbb{R}, {<})$ be the D1101: Strictly ordered set of real numbers such that
(i) $a, b \in \mathbb{R}$ are each a D993: Real number
The open real interval from $a$ to $b$ is the D11: Set \begin{equation} (a, b) : = \{ x \in \mathbb{R} : a < x, x < b \} \end{equation}
Child definitions
» D1509: Open real unit interval