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
Definition D3660
Countable map
Formulation 0
A D18: Map $x : J \to X$ is countable if and only if $J$ is a D16: Countable set.