A D11: Set $E \subseteq X$ is

**cofinite**within $X$ if and only if $X \setminus E$ is a D17: Finite set.

Definition D1880

Cofinite set

Formulation 0

Let $X$ be a D11: Set.

A D11: Set $E \subseteq X$ is**cofinite** within $X$ if and only if $X \setminus E$ is a D17: Finite set.

A D11: Set $E \subseteq X$ is

Results

▶ | R2615: Empty set is cofinite within a finite set |