First-countable space
id:
first-countable-space-236-15884335
title:
First-countable space
text:
In topology, a branch of mathematics, a first-countable space is a topological space satisfying the "first axiom of countability". Specifically, a space X is said to be first-countable if each point has a countable neighbourhood basis. That is, for each point x in X there exists a sequence N 1 , N 2 , … of neighbourhoods of x such that for any neighbourhood N of x there exists an integer i with N i contained in N . Since every neighborhood of any point contains an open neighborhood of that point
brand slug:
wiki
category slug:
encyclopedia
description:
Topological space where each point has a countable neighbourhood basis
original url:
https://en.wikipedia.org/wiki/First-countable_space
date created:
date modified:
2024-03-15T19:17:57Z
main entity:
{"identifier":"Q926996","url":"https://www.wikidata.org/entity/Q926996"}
image:
fields total:
13
integrity:
14