Q: What is a map? How do I use a map? Why is a map useful here?
A: Look at the WordCount and Friends programs from lecture. Remember that a map stores a relationship between a pair (known as a key to value relationship). Look at the example from the writeup that shows an initial dictionary of 9 words being split into different word families.
Java has a more detailed definition of a Map on the Java API.
Q: How do I store a complex structure as the values of a Map?
A: Review the Friends example from lecture.
Q: How do I call methods on the Sets that are in my Map?
A: Call get on the Map first. Then call methods on that. Review the Friends example from lecture.