Closure (Topology)/Examples/Open Interval in Open Unbounded Interval

Example of Closure in the context of Topology
Let $S$ be the open real interval:
 * $S = \openint a \to$

Let $H$ be the open real interval:
 * $H = \openint a b$

Then the closure of $H$ in $S$ is:
 * $H^- = \hointl a b$