Definition:Nowhere Dense

Definition
Let $T = \left({S, \tau}\right)$ be a topological space.

Let $H \subseteq S$.

Definition 2
A set $H$ is nowhere dense in $T$ iff $H^-$ contains no open set of $T$ which is not empty.

Equivalence of Definitions
These definitions can be seen to be directly equivalent from the definition of interior as the union of all subsets of $H$ open in $T$.

Example
The set $\left\{{\dfrac 1 n: n \in \N}\right\}$ is nowhere dense in $\R$.


 * Set of Reciprocals of Positive Integers is Nowhere Dense in Reals

Also see

 * Everywhere dense
 * Dense-in-itself