Concept clusters
Related ideas that live chapters apart, pulled onto one page — every factoring technique, every way to solve a quadratic, and more.
Which arrangement or distribution model do I need?
The decision path from a new problem's shape to one of Chapter 2's six models.
16 concepts →
Every counting-strategy move, in order
The full Chapter 1 pipeline for assembling a hard counting argument from scratch.
8 concepts →
Which function, partition, or relation count do I need?
The decision path from "how many maps/splits/relations" to the right count in Chapter 5.
8 concepts →
Which recurrence-solving method do I need?
The decision path from a new recurrence to first-order, characteristic-root, or generating-function methods.
8 concepts →