Editing Mathematical induction (section)

=== Induction on more than one counter ===
It is sometimes desirable to prove a statement involving two natural numbers, {{mvar|n}} and {{mvar|m}}, by iterating the induction process. That is, one proves a base case and an induction step for {{mvar|n}}, and in each of those proves a base case and an induction step for {{mvar|m}}. See, for example, the [[Proofs involving the addition of natural numbers|proof of commutativity]] accompanying ''[[addition of natural numbers]]''. More complicated arguments involving three or more counters are also possible.