【摘要】 <正> 1 引言时态数据库是将时间的概念结合到传统的数据库中。近十年来,人们对此所作的许多研究主要集中在把关系数据模型扩展为时态模型以及(或)把关系查询语言SQL和Quel扩展为时态的模式。除了强调关系模型之外,也有一些研究是将ER和其他的语义数据模型扩展到时态方面。时态数据模型的形式化和时态数据库的物理数据组织结构也受到了人们的关注。更多还原

【Abstract】 In this paper,a conceptual temporal model,which combines qualitative and quantitative temporal constraints ,is presented. In the model an event (temporal object) no longer corresponds to a single temporal interval (a temporal interval only represents an occurrence of the event). It is a set of intervals meeting the given constraints conditions. By adding specific temporal fields into a relational database arid defining a temporal view,each temporal object can be transformed into a visualized entity in the coordinate plane and a visualized temporal constraint propagation algorithm is introduced. This visualization methods and technique is helpful for understanding and analyzing a temporal network and detecting a consistent and robust solution in the network.更多还原