# SP20:Lecture 3 prep

Please come to lecture 3 knowing the following definitions (you can click on the terms or symbols for more information, or you can review the entire lecture notes from last semester here):

Definition: Subset
If and are sets, then is a subset of (written ) if every is also in

Definition: Power set
The power set of a set (written )is the set of all subsets of . Formally, .
Definition: Union
If and are sets, then the union of and (written ) is given by .
Definition: Intersection
If and are sets, then the intersection of and (written ) is given by .
Definition: Set difference
If and are sets, then the set difference minus (written ) is given by .