基于路径表达式的XML第四范式及无冗余性判定  

Fourth Normal Form and No Redundancy for XML Document Based on Path Expression

作　　者：张忠平[1] 刘志晓[1] 

机构地区：[1]燕山大学信息科学与工程学院,河北秦皇岛066004

出　　处：《小型微型计算机系统》2013年第5期1091-1096,共6页Journal of Chinese Computer Systems

基　　金：河北省自然科学基金项目(2012203087)资助

摘　　要：随着XML应用越来越广泛,为避免冗余,XML模式设计也变成了越来越受关注的问题,因此XML规范化理论是一个重要的研究领域.类似于关系数据库,本文从数据库角度出发,以消除数据冗余为目的,研究DTD中以路径表达式为基础的基本定义;因函数依赖和多值依赖是数据语义的重要组成部分,将其引入到XML领域中,形式化定义了XML的函数依赖和多值依赖;基于XML树、函数依赖和多值依赖概念,给出了键、冗余的描述,进而在XML函数依赖和多值依赖并存情况下,提出了满足XML第四范式的条件;给出了满足XML第四范式条件的XML文档树无冗余的判定定理,并通过具体实例及实验证明了XML第四范式的有效性.With XML becoming more and more popular, to avoid the redundancy, XML schema design has become an important issue. so the normalization of XML is a hotspot in research field. Similar to relational database, this paper is database based with the goal of eliminating the data redundancy, to study the concepts of path expression in DTD, in this paper XML is extended with functional dependency and multi-valued dependency, which are fundamental to semantic specification. And make formalized definition on functional dependency and multi-valued dependency of XML; Based on the concepts of XML tree and data dependency, it provides the description of key and redundancy. On the condition of the coexistence of functional dependency and multi-valued dependency, it further proposes the terms to meet the fourth normal form and provides theorem to determine the XML document tree which meets the above terms without redundancy, and the sound of the fourth normal form is proved by experiment.

关 键 词：XML规范化 函数依赖 多值依赖 键 冗余 第四范式 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]