ThmDex – An index of mathematical definitions, results, and conjectures.
Set of symbols
Deduction system
Zermelo-Fraenkel set theory
Binary cartesian set product
Binary relation
Binary endorelation
Preordering relation
Partial ordering relation
Ordering relation
Ordered set
Dedekind cut
Set of real numbers
Set of basic numbers
Definition D1699
Basic number
Formulation 0
Let $[-\infty, \infty]$ be the D1275: Set of basic numbers.
Then $x$ is a basic number if and only if \begin{equation} x \in [-\infty, \infty] \end{equation}