导　　师： 杨国纬

学科专业： H1201

授予学位： 博士

作　　者： ;

机构地区： 电子科技大学

摘　　要： 1988年m．gelfond和v．lifschitz共同为非单调逻辑编程创建了一种重要的模型语义-stable模型语义，并在1991年将该模型语义扩展并更名为answerset语义，由此发展出一种重要的非单调逻辑编程技术-answerset编程技术。作为该类编程技术的核心，answerset语义相对其它非单调逻辑编程语义理论简洁明了，它充分利用了逻辑编程领域的已有成果，有效地实现了逻辑程序的非单调推理。目前，answerset编程不仅被公认为一种重要的知识表示工具，而且是逻辑编程与非单调推理领域的研究热点。 在对answerset编程理论进行了探索性研究基础上，取得了如下创新性成果： 1．提出了一种利用基于answerset语义的权约束编程实现策略冲突自动消解的新方法。随着策略的广泛应用，关于其冲突消解的研究愈来愈受到重视。在目前存在的多种途径中，采用逻辑编程完成冲突消解具有自动化程度高、逻辑严谨等优点。但是，原有方法却存在被消解的冲突种类受限、优化机制单一等缺点。为克服以上缺陷，在完成策略语法与语义形式化定义、冲突捕获机制定义、冲突分类以及冲突消解特性分析的基础上，本文充分利用了权约束编程特有的集合选择紧凑表示能力以及灵活的优化语句，完成了冲突消解权约束程序建立等工作。该方法不但扩展了被消解的冲突种类，而且提供了更为合理和灵活的优化机制，有效地克服了原有方法的缺陷。 2．提出了一种基于事件的web服务组合新方法。随着电子商务的普及，有关web服务自动组合的研究愈来愈受到重视。目前主要存在基于ai(artificialintell-igence)规划和诸如uml(unifiedmodelinglanguage)技术的两类途径。但是，由于难以建立服务组合域，加之不完全信息的影响，因而前类方法难以实现，而后者由于描述能力不足，因此无法满足用户的多样化需求。为获得一种既易于实现又能满足用户多样化需求的服务组合的有效途径，本文在完成一种基于事件的服务语言定义、用于描述服务组合的组合方案建立机制以及服务互斥性质分析的基础上，通过answerset编程表示组合方案，以获得实现组合服务目标的组合轨迹。该方法充分利用了策略的动态执行能力和answerset编程丰富的表示能力，不但应该具有良好的应用前景而且能够满足用户的多样化需求。 3．利用answerset编程完成了er模型(entity-relationshipmodel)的逻辑表示。er模型是一种重要的语义数据模型(semanticdatamodel)，至今仍被广泛地应用于数据库设计中。针对er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，前者缺乏自动推理能力，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，本文在完成er模型分类研究、er模式语义与语法形式定义的基础上，利用answerset编程完成了er模式的逻辑表示。该方法不但为er模型提供了一种新的逻辑表示途径，而且有效地克服了基于描述性逻辑表示途径的缺陷。更为重要的是，它还为利用er模式实现异构数据库之间的语义协作提供了理论基础。 M. Gelfond and V. Lifschitz collaboratively established an important kind of model semantics-Stable model semantics for nonmonotonic logic programming in 1988, and expanded this model semantics and renamed it as Answer Set semantics in 1991. Based on this semantics, an important kind of nonmonotonic logic programming technology-Answer Set programming technology was developed. Constrasted with other semantics theories of nonmonotonic logic programming, Answer Set semantics, the kernel of Answer Set programming technology, is concise and simple, and fully utilizes the fruits acquired by the logic programming community, and effectively realizes nonmonotonic reasoning of the logic program. Nowadays, Answer Set programming is not only widely accepted as an important tool of knowledge representation but also a research focus of the logic programming and the nonmonotonic reasoning communities. Based on the investigation of Answer Set programming theory, the innovative contributions included in the thesis are summarized as follows: 1. A new method which utilizes weight constraint programming based on Answer Set semantics to automatically resolve the policy conflict is proposed. As policy being widely applied, more and more attention is paid to the policy conflict resolution. Among currently existing approaches, the conflict resolution methods based on logic programming have merits of logical preciseness, high automatization, etc. Whereas, the methods mentioned above have shortcomings, such as limited kinds of resolved conflicts and monotonic optimization mechanism. To overcome these shortcomings above, based on accomplishments of the formal definition of syntax and semantics of policy, the definition of conflict capture mechanism, the conflict classification and the analysis of conflict resolution characters, this thesis fully utilizes the compact representation capability of set selection and flexible optimization sentences of weight constraint programming, to accomplish the creation of weight constraint programs which are used to resolve conflict, etc. This method not only expands the kinds of resolved conflicts but also supplies flexible and multiple optimization mechanisms, thus it effectively overcomes the shortcomings of the previous methods. 2. A new Web services composition method based on events is proposed. As the prevalence of electronic business, more and more attention is paid to the Web services automatic composition research. Nowadays, there are two main approaches about Web services composition. One is based on AI /(Artificial Intelligence/) planning and the other is based on the technologies, such as UML /(Unified Modeling Language/). Whereas, the former is hardly realized for the difficulty of representation of services composition domain, and the influence of incomplete information. The latter can not satisfy the multiple requirements of users for the insufficient description capability. To obtain an effective approach that is able to satisfy the multiple requirements of the users and can be easily realized, based on accomplishments of a service language based on events, the mechanism to create the composite schema which is used to describe composite services and the analysis of the exclusive services' properties, this thesis utilizes Answer Set programming to represent the composite schema to obtain the composite trajectory which realizes the object of composite services. This method fully utilizes the dynamically executing capability of the policy and the expressive representation capability of Answer Set programming, thus it should have a good application prospect and can satisfy multiple requirements of the users. 3. The logic representation of ER Model /(Entity-Relationship Model/) is accomplished by Answer Set programming. ER Model is a well-known semantic data model and yet widely applied to the database design. Currently there are two main approaches about the improvements for ER model. One is based on the graphical representation and the other is based on the description logic representation. Whereas, the former has not automatic reasoning capability, the latter has shortcomings, such as the weak representation capability and insufficient compatibility with database. To overcome these shortcomings, based on accomplishments of research on the ER model classification, the formal definition of syntax and semantics of ER schema, this thesis utilizes Answer Set programming to represent ER Schema. This method not only supplies a new logic representation approach for ER model, but also effectively overcomes the shortcomings of the approach based on the description logic representation. More importantly, this works above supply the theoretic base for applying ER schema to realize the semantic interoperability among heterogeneous databases.

关 键 词： 编程 冲突消解 服务组合

分 类 号： [TP311.11]

领　　域： [自动化与计算机技术] [自动化与计算机技术]