The *complement* of a set A - denoted A’ or A^{c} - is the set of all elements in the universal set U that are not in A. If the Universal set is W - the set of all whole numbers - and E is the set of all even numbers, then E^{c} represents all elements of W that are not members of E. That is,

W = {0, 1, 2, 3, 4, 5, …}

E = {0, 2, 4, …}

E^{c} = {1, 3, 5, …} = the set of all odd numbers

If our universal set is the set of all chess pieces, U = { king, knight, rook, bishop, queen, pawn} and if K = {king, knight}, then K^{c} = {rook, bishop, queen, pawn}.

You will find that a set and its complement together form their universal set!

The *cardinality* of a set is the number of elements in the set. For example, if A = {1, 3, 0, 7, 9}, then the cardinality of A is represented as |A| = 5. Going back to the chess pieces example, the number of elements in set U is 6, set K is 2, and set K^{c} is 4. This satisfies the relation

|U| = |K| + |K^{c}|

The `len()`

function of Python can be used to find the cardinality of a set. The `.difference()`

method returns a set that contains the items that only exist in one set and not the other. `U.difference(K)`

will return the set K^{c}.

### Instructions

**1.**

Write code in Python to create a set of the blue component colors in the rainbow, `B`

= {blue, indigo, violet}.

**2.**

Use the difference method on sets `R`

and `B`

to find B^{c}.

Assign this set to a variable called `Bc`

and then print the contents of `Bc`

.

**3.**

Verify that |R| = |B| + |Bc|.