1.The old interface is no longer a proper subset of the new one.
旧接口不再是新接口的固有子集。
2.No non-prime attribute in the table is functionally dependent on a part (proper subset) of a candidate key.
不存在非主属性对任一候选键的部分函数依赖。
3.set empty set, null set Venn diagram union intersection universal set proper subset solution set
集合空集维恩图并集交集全集真子集解集有关代数，方程，不等式
4.There is not an open closed non-empty proper subset in the Rn
Rn中不存在既开又闭的非空真子集