Counting Basics Ladder¶
Who This Is For¶
Use this ladder when you can already manipulate formulas, but you want to get better at inventing the counting model instead of searching for a memorized identity.
Warm-Up¶
- permutations vs combinations
- independent-choice counting
Core¶
- disjoint-case splits
- stars and bars
- run counting
Example Notes¶
Exit Criteria¶
You are ready to move on when you can:
- say clearly whether order matters
- split a count into disjoint cases without overlap
- recognize stars-and-bars structure
- explain a formula as a construction, not just as a symbol string