Compact Subset of Hilbert Sequence Space is Nowhere Dense

Theorem
Let $A$ be the set of all real sequences $\left\langle{x_i}\right\rangle$ such that the series $\displaystyle \sum_{i \mathop \ge 0} x_i^2$ is convergent.

Let $\ell^2 = \left({A, d_2}\right)$ be the Hilbert sequence space on $\R$.

Let $H$ be a compact subset of $\ell^2$.

Then $H$ is nowhere dense in $\ell^2$.

Proof
By Compact Subset of Hilbert Sequence Space is Closed, $H$ is a closed set of $\ell^2$.

From Set is Closed iff Equals Topological Closure:
 * $H^- = H$

where $H^-$ denotes the closure of $H$.

From Subset of Hilbert Sequence Space with Non-Empty Interior is not Compact:
 * $H^\circ = \varnothing$

where $H^\circ$ denotes the interior of $H$.

Thus:
 * $\left({H^-}\right)^\circ = \varnothing$

and the result follows by definition of nowhere dense.