necessary and suftqcient conditions

• 充要条件

necessary and suftqcient conditions的用法和样例：

例句

1. Necessary and suffcient conditions for the existence of such strategies are established.
   建立了关于这类策略存在的充要条件。
2. Finally, sufficient and necessary conditions for a fuzzy good congruence on an adequate semigroup to be idempotent-separated are proved.
   最后，得到了适当半群上的模糊好同余为幂等可分的充要条件。