Editing Mathematical proof (section)

===Proof by exhaustion===
{{Main|Proof by exhaustion}}
In proof by exhaustion, the conclusion is established by dividing it into a finite number of cases and proving each one separately. The number of cases sometimes can become very large. For example, the first proof of the [[four color theorem]] was a proof by exhaustion with 1,936 cases. This proof was controversial because the majority of the cases were checked by a computer program, not by hand.<ref>See [[Four color theorem#Simplification and verification]].</ref>