粗关系数据库中的粗函数依赖研究

The Reseach of Rough Functional Dependency in Rough Relational Databases

以粗集理论为研完方法,针对粗关系数据库属性值非原子性的特点,从语义等价的角度改进了已有的粗关系数据库函数依赖定义,提出了其修正定义粗函数依赖,使之更客观地反映粗关系数据库中数据的语义联系,体现现实世界不确定性信息的粗糙性和不完备性。本文还给出了判断粗函数依赖是否成立的算法,并用粗关系实例验证了粗函数依赖的优越性,探讨了基于粗函数依赖的推理规则。

With Rough Sets Theory as a method,the concept of functional dependency in rough relational databases is modified from the view of semantic equipollence in connection with the characteristic of non-atom in values of rough relational databases. The modificatory concept - rough functional dependency is proposed ,so that it can objectively refleet the connections among the data of rough relational database and embody the roughness and incompleteness of the information in the real world. The algorithm on how to judge whether a rough functional dependency holds is also introduced. Additionally ,this paper verifies the advantage of rough functional dependency by a rough relational database example. The inference rules based on rough functional dependency are discussed finally.