充要条件英文

必要条件 necessary condition

Sufficient Condition:Whenver one thing ensures, is enough for, or guarantees that another thing is true. In other words, a conditon A is sufficient for a condition B if and only if the truth of A guarantees the truth of B.Necessary Condition:Whenever one thing is essential or required for another thing to be true. In other words, a condition A is necessary for a condition B if and only if the falsity of A guarantees the falsity of B.

necessity [英] [nisesiti] [美] [nssti] 必要(性)

sufficient condition 是充分条件necessary condition 是必要条件若A是B的充分条件则A可以推出B表示为A->B若B是A的必要条件则B可以推出A表示为A<-B范围大的可以推出范围小的成立，但是范围小的推不出范围大的是否成立