5 Sets

• $\{x, y\}$ : a set consisting of two values, $x$ and $y$
• $\{\}$ : the empty set
• $x \in S$ : value $x$ is an element of set $S$
• $S \cap T$ : the intersection of sets $S$ and $T$
• $S \cup T$ : the union of sets $S$ and $T$
• $S T$ : the difference of sets $S$ and $T$
• $S \subset T$ : $S$ is a proper subset of $T$ .
• $S \subseteq T$ : $S$ is a subset of $T$ .
• $S - x$ : same as $S \{x\}$ .
• $S \times T$ : the Cartesian product of $S$ and $T$ .
• $\{x\vert P(x)\}$ : a set consists of all values $x$ such that $P(x)$ is true.
• $\prod_{i=1}^{n} X_i$ : the Cartesian product of $X_1, X_2,\ldots X_n$ .
• $\vert S\vert$ : the number of items in set $S$ .
• $\mathcal{P}(S)$ : the power set of set $S$ .