01.5 Constructive vs Classical Viewpoints
1.5 Constructive vs Classical Viewpoints Mathematics has more than one standard way to interpret proof. The two most important viewpoints are classical and constructive mathematics. Classical mathematics accepts the usual laws of logic, including the law of excluded middle: P or not P For any proposition P , classical logic says that either P is true or P is false. This principle allows indirect proofs. To prove that an object...