0. Set of symbols
1. Alphabet
2. Deduction system
3. Theory
4. Zermelo-Fraenkel set theory
5. Set
6. Binary cartesian set product
7. Binary relation
8. Map
9. Function
10. Real function
11. Euclidean real function
12. Basic real function
13. Basic rational function
14. Basic integer function
Basic natural number function
Formulation 0
Let $\mathbb{N}$ be the D225: Set of basic natural numbers.
A D18: Map $f : X \to Y$ is a basic natural number function if and only if \begin{equation} Y \subseteq \mathbb{N} \end{equation}
Child definitions
» D218: Basic boolean function
» D5406: Basic positive integer function
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