- A set is a collection of objects where the individual items are elements or members, e.g $\{apple, banana, orange\}$
- orange ∈ A, kiwi ∉ A
- {}, ∅ empty set
Venn diagrams
- Members of a set are displayed within a closed curve
- Subsets, universal set
- Intersection of sets: A∩B
- $A'$: set of all elements not in A, "absolute complement of A"
- $n(A), |A|$: cardinality of the set
- Union of sets $A∪B$: set that belongs to A, B or both A & B
- $A /\ B:$ relative complement of Set B in A (A - B)
- If A us a subset of B, B is a superset of A
- B is a strict subset of A if $n(A)$ does not equal $n(B)$