## 2.3. The Principle of Induction

### Definition 2.3.7: Recursive Definition

Let

**S**be a set. If we define a function*h*from**N**to**S**as follows:*h(1)*is a uniquely defined element of**S***h(n)*is defined via a formula that involves at most terms*h(j)*for*0 < j < n*

*h*from**N**to**S**.