Category:Excluded Set Topology

This category contains results about excluded set topologies.

Let $S$ be a set which is non-empty.

Let $H \subseteq S$ be some subset of $S$.

We define a subset $\tau_{\bar H}$ of the power set $\powerset S$ as:

$\tau_{\bar H} = \set {A \subseteq S: A \cap H = \O} \cup \set S$

that is, all the subsets of $S$ which are disjoint from $H$, along with the set $S$.

Then $\tau_{\bar H}$ is a topology called the excluded set topology on $S$ by $H$, or just an excluded set topology.