摘要： 模糊数据库由于其所含信息的模糊性,可分解为现实世界的多种可能性状态。在已有研究的基础上,对基于Vague关系数据模型的Vague连接操作进行研究,并在限定条件下,给出一个Vague外键连接操作计算公式。该公式可直接用于Vague数据库,可避免对Vague数据库对应的所有可能性状态逐一进行操作,且查询结果满足性质rep(q (T )) = q (rep(T ))。与基于可能性状态的查询方法相比,该方法的查询结果有效且具有较高的执行效率。

关键词: 模糊集, Vague集, 可能性状态, Vague关系数据模型, 连接操作, 复合操作

Abstract: The fuzzy database has a canonical interpretation as a set of regular databases because of the fuzzy information.On the basis of existing research,a vague join operation based on the vague relational data model is discussed,and a formula of vague foreign key join under constrained conditions is given.The key for efficiency resides in the fact that the formula does not require to make computations explicitly over all the possible states,but works directly on the vague relational databases,and the query results satisfy rep (q(T))=q(rep(T)).Compared with other query methods based on the possible states,query results of the method are valid and have high execution efficiency.

Key words: fuzzy set, Vague set, possibility state, Vague relational data model, join operation, composite operation

中图分类号: 

• TP311