Interior point of a set

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2010 Mathematics Subject Classification: Primary: 54A [MSN][ZBL]

in a topological space

A point $x$ of a given set $A$ in a topological space for which there is an open set $U$ such that $x \in U$ and $U$ is a subset of $A$. If $x$ is an interior point of a set $A$, then $A$ is said to be a neighbourhood of the point $x$ in the broad sense. The interior of a set $A$ consists of the interior points of $A$.

How to Cite This Entry:
Interior point of a set. Encyclopedia of Mathematics. URL:
This article was adapted from an original article by S.M. Sirota (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article