【摘要】 <正> 1 引言主动数据库的主动特性一般使用E-C-A(Event-Condi-tion-Action)规则模型描述。我们用CA规则表示ECA规则模型中的Condition和Action部分,ECA规则语言的语义可描述为:事件E的发生可触发CA规则的执行,该CA规则的执行又可导致其它事件的发生,进而触发其它CA规则的执行,形成触发规则集。主动规则源于人工智能的知识表示的产生式系统(OPS5),许多主动数据库规则系统的执行语义均源于OPS5产生式规则语言的recognize-act cycle算法(如图更多还原

【Abstract】 Many active database systems propose various rule systems, which are normally described in an informal manner. The informal description makes it difficult to understand the behavior of rules and the differences of various rule systems. In this paper,we describe a denotational semantic for a kind of graph-based rule in an active database. The kind of active rules had been formally defined and analyzed in our previous paper ,their execution may be both inter-rule and intra-rule parallelism through a nested transaction model.更多还原