Definitions
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Results
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Conjectures
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Set of symbols
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Alphabet
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Deduction system
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Theory
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Zermelo-Fraenkel set theory
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Set
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Binary cartesian set product
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Binary relation
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Binary endorelation
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Preordering relation
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Partial ordering relation
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Partially ordered set
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Closed interval
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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