Definition:Regular Closed Set

Definition

Let $T$ be a topological space.

Let $A \subseteq T$.

Then $A$ is regular closed in $T$ if and only if:

$A = A^{\circ -}$

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

Also see

• Definition:Regular Open Set

• Results about regular closed sets can be found here.

Sources

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