Dirichlet判别法必要性的证明

Proof for the necessity of Dirichlet criterion

针对很多文献中往往只是指出Dirichlet判别法是充分的,本文通过构造的方法证明了Dirichlet判别法的条件不仅是充分的,而且是必要的.

In some scientific and technical literatures, it is always pointed that the judgement of Dirichlet is a sufficient condition, While in this paper, it is also proved that the judgement of Dirichlet is a necessary condition with the help of the sturcture method.