Source: wikibot/cocountable-topology
= Cocountable topology
{wiki=Cocountable_topology}
Cocountable topology is a specific type of topology defined on a set where a subset is considered open if it is either empty or its complement is a countable set. More formally, let \\( X \\) be a set. The cocountable topology on \\( X \\) is defined by specifying that the open sets are of the form \\( U \\subseteq X \\) such that either: 1. \\( U = \\emptyset \\), or 2.