Sets: List of terms
Set
Any collection of objects
Empty set 
A set that has no elements
Universal set U
A set that contains all elements, everything
Subset X  Y
X is a subset of Y iff all elements in X are in Y
The empty set is a subset of all sets
Proper subset
X Y
X is a proper subset of Y iff X is a subset of Y and X  Y
Union of X and Y
XY
A set whose elements are either in X or in Y or in both X and Y
Intersection of X
and Y: X  Y
A set whose elements are in both X and Y, the common elements of X and Y
Difference of X and A set that consists of those elements in X that are not in Y
Y: X - Y
Compliment of a set A set that consists of all elements in the universal set that are not in X:
X: ~X
~X = U - X
Disjoint sets
Sets that don’t have common elements, X  Y = 
Venn Diagrams
Pictorial views of sets
Set identities
Laws about relations between sets, correspond to the logical equivalences
Power set P (X)
The set of all subsets of X is called its power set
Partition of a set X
A set of subsets of X such that each element in X is found exactly in one of these
subsets, i.e. the subsets are disjoint and their union equals X
Ordered pair of
elements
A pair where each element has a specified position – first or second
Cartesian product of The set of all ordered pairs where the first element is in X, the second element is
X and Y, X x Y
in Y