ThmDex – An index of mathematical definitions, results, and conjectures.
Set of symbols
Alphabet
Deduction system
Theory
Zermelo-Fraenkel set theory
Set
Binary cartesian set product
Binary relation
Map
Function
Real collection function
Euclidean real function
Real function
Rational function
Integer function
Natural number function
Definition D5406
Positive integer function
Formulation 0
A D18: Map $f : X \to Y$ is a positive integer function if and only if \begin{equation} Y \subseteq \{ 1, 2, 3, \ldots \} \end{equation}