A D11: Set $E \subseteq X$ is

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

▾ Set of symbols

▾ Alphabet

▾ Deduction system

▾ Theory

▾ Zermelo-Fraenkel set theory

▾ Set

▾ Binary cartesian set product

▾ Binary relation

▾ Map

▾ Bijective map

▾ Set of bijections

▾ Countable set

▾ Finite set

▾ Alphabet

▾ Deduction system

▾ Theory

▾ Zermelo-Fraenkel set theory

▾ Set

▾ Binary cartesian set product

▾ Binary relation

▾ Map

▾ Bijective map

▾ Set of bijections

▾ Countable set

▾ Finite 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