Our research project started from 1999 , since research on xml - based semistructured data is relatively recent , and only a few of the topics have been addressed , the goal of which is to do some preliminaries for theoretical and foundation issues on xml - based semistructured data so as to lay a solid groundwork for the further development of practical systems 本文对基于xml的半结构数据的管理及集成进行了较为全面而深入的研究和探讨，包括基于xml的半结构数据模型、查询语言、模式发现及抽取、视图机制、 xml半结构数据的存储以及数据集成等问题。
Different from the previous work , kf - diff + is tailored to both ordered trees and unordered trees . while dealing with the key path , the notion of the key constraint for semi - structure data and the notion of the multi - instance based keys are identified , which will greatly simplify the complexity of the algorithm 在特征路径相关的计算中，本文引入面向半结构数据的key约束思想，并且针对先前判定算法过于复杂的问题，提出了基于多实例结点集合的key约束的概念以及相关的处理方法，在一定程度上简化了计算。
