Definition:Adherent Point/Definition 1

Definition

Let $T = \left({X, \tau}\right)$ be a topological space.

Let $A \subseteq X$.

A point $x \in X$ is an adherent point of $A$ iff every open neighborhood $U$ of $x$ satisfies $A \cap U \ne \varnothing$.

Sources

• Lynn Arthur Steen and J. Arthur Seebach, Jr.: Counterexamples in Topology (1970)... (previous)... (next): $\text{I}: \ \S 1$: Limit Points