Symbols:V

Closed Set

 * $V$

Frequently used, and conventionally in many texts, to denote an closed set in the context of topology.

Variance

 * $\var X$

Let $X$ be a discrete random variable.

Then the variance of $X$, written $\var X$, is a measure of how much the values of $X$ vary from the expectation $\expect X$, and is defined as: