次协调数据库中的域关系演算

Domain Relational Calculus for Paraconsistent Database

次协调数据库的数据模型是用来处理数据库中两类不确定信息,即不完全信息和不一致信息(矛盾信息)。关系演算语言是表达关系数据模型中的数据操作的一种方式。域关系演算是以域为变量进行的关系演算。文中提出了一种4值的域关系演算来查询次协调数据库,它的语法与普通关系上的2值域关系演算相似,但是这种新的4值语义能够有效的查询不完全信息和不一致信息。这为次协调数据库中的类SQL语言及实现提供了理论依据,进而为次协调数据库的应用打下坚实基础。

Paraconsistent database is introduced to manipulate two kinds of uncertain information in database：incomplete and inconsistent.Relational calculus language is one way to express the operation of relational data mode1.Domain relational calculus bases on the variable of domain.In this paper,we present a 4-valued domain relational calculus for posing queries to paraconsistent databases based on that model.The syntax of our calculus is similar to that of the regular 2-valued relational calculus on ordinary relational databases,but our new 4-valued semantics makes it a useful querying tool for applications containing incomplete and inconsistent information.These results help establish the application of paraconsistent database.