Worked Example 22.1.1.
How many different
Solution.
We will use the Division Rule, first imposing additional structure on each possible study group. Within a study group, create positions of President, Vice-President, Secretary, and Janitor (cards, anyone?). Then there are
But a real study group doesn’t have this structure, so we’ll consider two structured groups to be equivalent when they have the same membership, regardless of positions. How many equivalent structured groups with a given membership are there? Within a group of four, the additional structure is just an ordering, and the number of orderings of a given group is
