E-R模型的回答集编程表示

Answer Set Programming Representation for E-R Model

作为一种广为接受的语义数据模型,E-R模型被广泛地应用于数据库设计阶段.但是E-R模型自身却存在某些缺陷,这些缺陷制约了对其进一步的应用.针对E-R模型的改进,目前主要存在基于图形表示和描述性逻辑表示两种途径.但是,前者仍然不具有自动推理能力,而后者却存在表示能力弱、与数据库兼容性不足等缺陷.为克服以上缺陷,提出一种利用回答集编程(answer set programming)表示E-R模型的新方法.首先,对应于数据库的E-R模式被区分为基本和扩展两种类型,并分别完成它们的语法与语义定义.其次,利用回答集编程完成以上两类模式的逻辑编程表示.最后,完成表示的正确性证明.提出的方法不仅为E-R模型提供了一种新的逻辑表示途径,而且相对原有的两种E-R模型改进途径具有明显的优势.更为重要的是该研究成果使得应用E-R模型实现异构数据库之间的语义协作成为可能.

As a well-known semantic data model,E-R model is widely applied in the database design phase. But,E-R model itself has some defects,and these defects restrict the further applications of the model. Currently there are two main approaches about the improvements for E-R model. One is based on the graphical representation and the other is based on the description logic representation. Whereas,the former still has not automatic reasoning capability,and the latter has some shortcomings such as the weak representation capability and the insufficient compatibility with relational database. To overcome these shortcomings,a novel method is proposed which utilizes the answer set programming to represent E-R Model. Firstly,E-R schemata corresponding to the databases are distinguished as the basic and the extended types,and then their syntax and semantic definitions are accomplished. Secondly,the answer set programming is utilized to accomplish the representations of the two types of the schemata above. Finally,the correctness of these representations is proved. The proposed method not only supplies a new logic representation approach for E-R model,but also has some obvious advantages over the two common used improvement approaches. More importantly,the results of this paper make it possible to apply E-R model to realize the semantic interoperability among heterogeneous databases.