Definition:Density of Topological Space

Definition
Let $T$ be a topological space.

The density of $T$ is the smallest cardinality of dense subset of $T$:


 * $d \left({T}\right) := \min \left\{{\left\vert{A}\right\vert: A \subseteq T \land A}\right.$ is dense$\left.{}\right\}$