偏序时态模式下规范覆盖问题  

Research on canonical cover in partial order temporal scheme

作　　者：万静[1] 邹积民[1] 

机构地区：[1]哈尔滨理工大学计算机科学与技术学院,哈尔滨150080

出　　处：《计算机应用研究》2011年第7期2473-2475,共3页Application Research of Computers

基　　金：黑龙江省自然科学基金资助项目(F201014)

摘　　要：目前有效的多时间粒度时态数据库设计方法多针对全序时态模式,当时态模式的时态类型集为偏序集时,由于涉及时态类型间的最大下界等操作而使其难以实现。针对偏序时态模式的规范覆盖问题进行研究,提出了偏序TFD(时态函数依赖)集有限闭包、偏序模式属性集有限闭包、偏序无冗余覆盖和偏序规范TFD集等概念,解决了偏序TFD成员籍问题;并给出了偏序TFD集的规范覆盖算法,对其正确性进行了证明,对算法的时间复杂度进行了分析。为偏序时态模式的综合范式分解问题研究奠定基础。Existing effective design methods of temporal database with multiple time granularities are almost designed for totally-ordered temporal scheme,it can hardly he used for partial-ordered temporal scheme because of complex operations such as greatest lower bound applied to temporal types. This paper investigated canonical cover of partial-order temporal scheme, gave the concepts of partial-order TFD （ temporal functional dependency ） set limited closure, partial-order scheme attribute set limited closure,partial-order non-redundant cover and partial-order canonical TFD set etc. Solved the membership problem of partial-order TFD. It also proposed the partial-order TFD set＇ s canonical cover algorithm. And gave the proof for its correction and the time complexity analysis. It sets the foundation for research of synthesis normal form decomposition in partial-order temporal scheme.

关 键 词：多时间粒度 偏序时态模式 偏序模式属性集有限闭包 偏序TFD集规范覆盖 

分 类 号：TP311.13[自动化与计算机技术—计算机软件与理论]