1.4   INDUCTION FROM A USER’S PERSPECTIVE

In this section we will review the two widely used forms of induction, complete (or strong) induction (also called course-of-values induction) and simple induction. We will see how they are utilized, and when one is more convenient than the other; relate them to each other, but also to another principle that is valid on natural numbers, the least (integer) principle.

1.4.1   Complete, or Course-of-Values, Induction

Suppose that Images(n) is a “property”—that is, a formula of one free variable, n—of the natural number n. To prove that Images(n) holds for all n Images Images it suffices to prove for the arbitrary n that Images(n) holds.

What we mean by “arbitrary” is that we do not offer the proof of Images(n) for some specific n such as n = 42; or n even; or any n that has precisely 105 digits, etc. If the proof indeed has not cheated by using some property of n beyond the generic “

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