Power Set

Definition

$\wp (X)$ of $X$ consists of all the subsets of $X$.

Amount of Elements in a Power Set

Lets say we have $|X|$:
$|X|=|\{1,\dots ,n\}|$
The $\wp (X)$ would have $2^n$ elements in the set.

Example

$X=\{1,2\}$
$\wp (X)=\{\varnothing ,\{1\},\{2\},X\}$