Definition:Regular Closed

Definition

Let $X$ be a topological space.

Let $A \subseteq X$.

Then $A$ is regular closed in $X$ iff:

$A = A^{\circ -}$

That is, if $A$ equals the closure of its interior.

Also see

• Regular Open

Sources

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