XML环的定义、分类、判定和消除

Definition,Classification,Judgment and Elimination of XML-cyclic

在关系数据库中,无环数据库模式设计是数据库理论与图论相结合而产生的一个新的研究领域.这里的环指的是在关系数据库中由于某些属性存在二义性,使得在查询这些属性的时候存在两条或两条以上的路径,这就形成了环.同样的,在XML文档中也存在着环.为了研究XML文档中的环,基于DTD提出了XML环的概念,分析了存在环结构的DTD,并对XML环进行了分类,给出XML环的判定算法,最后提出了消除XML环的方法.

Acyclic database scheme designing is a new research field in relational database; it combines database theory with graph theory. The cycle here means that some attributes are ambiguous in relational database, there are two or more paths when query about these attributes, so the cycle has formed. Cycle exist in the XML document in the same. For studying cycle in XML document, this paper have put forward conception of XML-cycle, analyzed DTD with cycle structure, classified the XML-cycle, given a determinant arithmetic and put forward a method to eliminate XML-cyclic in DTD at last.