# first axiom of countability

- See under axiom of countability.

# axiom of countability

- the property satisfied by a topological space in which the neighborhood system of each point has a base consisting of a countable number of neighborhoods (first axiom of countability) or the property satisfied by a topological space that has a base for its topology consisting of a countable number of subsets of the space (second axiom of countability).

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