| 1 | Mathematics can be said to be required to build on the achievements is indelible. | |
| 2 | In this paper, the definition of reductio ad absurdum, logical principles and problem-solving steps. | |
| 3 | By reductio, there cannot possibly be a procedure that acts like the mythical P. | |
| 4 | In other some sufficient conditions, by using reduction to absurdity, we prove there is no positive periodic solution. | |
| 5 | You can' t prove a negative nor recreate history to show what might have been. |