Decomposition for a new kind of imprecise information system  

作　　者：Shaobo DENG Sujie GUAN Min LI Lei WANG Yuefei SUI 

机构地区：[1]School of Information Engineering, Nanchang Institute of Technology, Nanchang 330099, China [2]Key Laboratory of Intelligent Information, Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190, China

出　　处：《Frontiers of Computer Science》2018年第2期376-395,共20页中国计算机科学前沿（英文版）

基　　金：Acknowledgements This work was partially supported by the Science and Technology Project of Jiangxi Provincial Department of Education （GJJ 161109, GJJI51126）, the National Natural Science Foundation of China （Grant Nos. 61363047, 61562061）, and the Project of Science and Technology Department of Jiangxi Province （20161BBES0051, 20161BBES0050）.

摘　　要：In this paper, we first propose a new kind of imprecise information system, in which there exist conjunctions （∧＇s）, disjunctions （∨＇s） or negations （ ＇s）. Second, this paper discusses the relation that only contains ∧＇s based on relational database theory, and gives the syntactic and semantic interpretation for A and the definitions of decomposition and composition and so on. Then, we prove that there exists a kind of decomposition such that if a relation satisfies some property then it can be decomposed into a group of classical relations （relations do not contain ∧） that satisfy a set of functional dependencies and the original relation can be synthesized from this group of classical relations. Meanwhile, this paper proves the soundness theorem and the completeness theorem for this decomposition. Consequently, a relation containing ∧＇s can be equivalently transformed into a group of classical relations that satisfy a set of functional dependencies. Finally, we give the definition that a relation containing ∧＇s satisfies a set of functional dependencies. Therefore, we can introduce other classical relational database theories to discuss this kind of relation.In this paper, we first propose a new kind of imprecise information system, in which there exist conjunctions （∧＇s）, disjunctions （∨＇s） or negations （ ＇s）. Second, this paper discusses the relation that only contains ∧＇s based on relational database theory, and gives the syntactic and semantic interpretation for A and the definitions of decomposition and composition and so on. Then, we prove that there exists a kind of decomposition such that if a relation satisfies some property then it can be decomposed into a group of classical relations （relations do not contain ∧） that satisfy a set of functional dependencies and the original relation can be synthesized from this group of classical relations. Meanwhile, this paper proves the soundness theorem and the completeness theorem for this decomposition. Consequently, a relation containing ∧＇s can be equivalently transformed into a group of classical relations that satisfy a set of functional dependencies. Finally, we give the definition that a relation containing ∧＇s satisfies a set of functional dependencies. Therefore, we can introduce other classical relational database theories to discuss this kind of relation.

关 键 词：imprecise information systems DECOMPOSITION composition soundness and completeness 

分 类 号：TP309[自动化与计算机技术—计算机系统结构] O151.21[自动化与计算机技术—计算机科学与技术]