Techniques of proof I: Direct method
Sometimes the simple approach is the best.
Our first method for proving theorems is the most straightforward and is called the direct method. Most statements can be broken down into smaller statements of the form ‘If A, then B.’ To prove A implies B directly you prove A implies A1, prove A1 implies A2, A 2implies A3 and so on until you get Ar implies B. Then you have proved A B. Each ...