一种关系数据库到本体的自动构建方法

随着语义网的发展,对本体的需要也越来越大。但是目前大多数的数据被存储在关系数据库中,这些数据不能被语义网应用程序所访问。因此如何将关系数据中的数据转化为可以被语义网应用的数据,是一个需要解决的问题。针对上述问题,提出了一种从数据库自动地构建OWL本体的方法。该方法把本体构建过程分为语义信息的发现和本体映射两个部分。并且定义了一种图M-Graph,通过M-Graph的生成与分析,结合映射规则自动地构建OWL本体。实验验证,该方法可自动地由关系数据库构建OWL本体,并且可以得到相对丰富和准确的本体。     

基于细胞元本体的标准件库资源共享研究

针对目前标准件库不支持异构CAD系统和标准件信息不完整两个主要问题,提出了一种基于细胞元本体的标准件库资源共享方法。该方法使用Web本体描述语言(Web Ontology Language,OWL)表示细胞元本体模型,制定语义映射规则,以细胞为转换单元,屏蔽了信息表示的异构性,使应用本体和细胞元本体成为具有语义关系的逻辑上的整体,实现了异构CAD系统对标准件库的共享及异构数据的实时转换。该方法应用在Pro/E,UG和CATIA3个CAD平台的同步协同设计中,证明了其可行性。     

本体复用方法语义导入的研究与设计

在OWL(web ontology language)中,本体复用主要采用owl:imports.然而,这种复制 粘贴的方式会出现若干问题.基于此,提出一种新的导入原型:语义导入.在本体空间中支持TBox推理机推理和语义导入,以促进本体复用.提出一种基于ALC本体语义导入的TBox推理分布式算法,解决了简单本体空间中Tableaux算法的逻辑推理问题.     

基于OWL本体论映射的数据库网格语义模式集成研究

本文提出了一种在数据库网格中OWL本体论映射机制如何用于基于语义的数据库模式集成。方法是首先把关系模式转化为RDF/OWL语义描述以完成局部映射,再通过把局部数据语义与全局共享本体建立联系来完成全局映射。本质是把异构数据库模式的语义通过本体显性地表达出来,并在语义Web层完成模式的集成。特点是实现了在统一的语义层次上进行共享与查询,同时采用了局部映射与全局映射松耦合的构架,其特有的分层结构使得在跨库/单库环境中进行语义查询变得更加灵活。     

从ER模式到OWL DL本体的语义保持的翻译

提出了一种从ER模式到OWL DL本体的语义保持的翻译方法.该方法在形式化表示ER模式的基础上,建立ER模式和OWL DL本体之间精确的概念对应,通过一个翻译算法按照一组预定义的映射规则实现模式翻译.理论分析表明,该方法是语义保持的和有效的;算法实现和案例研究进一步证实,完全自动的机器翻译是可实现的.该文方法是原创性的,为Web本体的开发以及数据库和语义Web之间语义互操作的实现开辟了一条有效途径.     

装配公差综合领域本体知识库的构建

为了减少机械产品设计过程中的不确定性,解决装配公差信息在异构CAX系统中共享性差和传递不畅的问题,利用本体丰富的语义知识和语法结构,通过分析装配公差综合领域相关知识,采用网络本体语言OWL定义其中的概念和关系,并采用语义网规则语言SWRL定义其中的约束条件和分配经验。将基于OWL的结构化知识转换成事实、基于SWRL的约束化知识转换成规则,并在推理引擎的基础上构建装配公差综合领域本体知识库。同时开发了基于本体的装配公差综合原型系统,实现了装配公差类型和装配公差值的自动生成。     

语义虚拟环境本体可视化模型的研究

当前信息可视化所面临的一个瓶颈就是,需要一种模型来把场景图形内容和特定领域的语义信息进行有效集成,使用户可以有效地解释个性化可视化信息。基于X3D标准以及本体用本体描述语言OWL描述X3D标准,构建了一个X3D标准本体和一个映射本体来实现X3D标准本体和其他具体领域本体之间类和属性的映射,以达到丰富虚拟场景语义的目的。基于X3D标准本体和映射本体设计了语义虚拟环境本体可视化模型,从而为具体领域本体实现可视化提供了一种方法。实验结果证明了该模型的可行性。     

基于UML类图的OWL本体映射方法

传统的本体构建在抽取关键观念和关系时,各领域专家的参与增加了构建领域本体的成本,限制了以领域本体为基础的语义两的发展和普及。针对该问题,通过分析UML类图和OWL的异同点,提出从现有UML模型中提取本体的概念、属性、关系、约束等领域知识并将其映射为OWL本体的方法,利用该方法将加油卡发行UML模型成功转换为OWL本体,从而实现本体创建的经济性和高效性。     

大规模定制下基于本体的服务产品配置研究*

为了研究服务产品大规模定制的实现,探讨了服务产品大规模定制的实现机理和关键技术,指出模块化设计对服务产品族及服务产品平台的重要性。在服务产品模块化设计的基础上,为了提高服务产品配置知识的共享性和重用性,提出了一般服务产品配置的模型和概念,结构化了服务产品配置的构件和模块,建立了服务产品配置本体。采用网络本体语言OWL形式化服务产品配置的结构知识,采用语义网规则语言SWRL编码服务产品配置的约束知识,并分别映射到JESS推理系统的知识库和规则库中,使用JESS推理机执行推理过程,产生配置结果。为说明该方法的     

基于关系数据库存储OWL本体的方法研究

在研究OWL本体的存储模式和现有的基于关系数据库本体存储模式的基础上,本文提出了一种新的基于关系数据库存储OWL本体的方法。该方法根据OWL的构词特征,设计关系表来保存本体中资源之间的关系,描述了特征和约束、刻画了本体的层次和等价等关系,很好地存储了本体的语义信息。它适用于存储大规模的本体,同时大大提高了检索、查询、映射的效率。     

基于本体的分布式CBR设计系统

提出了一种分布式基于案例推理设计系统框架。该框架通过本体服务器在分布式案例库之间建立共享本体,每个案例库在共享本体的约束和指导下可以灵活地表示各自的领域知识。各案例库的知识表示都遵循共享本体约定,实现了知识集成。系统采用Web Service技术构建,能够实现分布式异构环境下的系统集成。该框架是一个开放的系统框架,具有很强的可扩展性。     

A legal case OWL ontology with an instantiation of Popov v. Hayashi

The paper provides an OWL ontology for legal cases with an instantiation of the legal case Popov v. Hayashi. The ontology makes explicit the conceptual knowledge of the legal case domain, supports reasoning about the domain, and can be used to annotate the text of cases, which in turn can be used to populate the ontology. A populated ontology is a case base which can be used for information retrieval, information extraction, and case based reasoning. The ontology contains not only elements for indexing the case (e.g. the parties, jurisdiction, and date), but as well elements used to reason to a decision such as argument schemes and the components input to the schemes. We use the Protégé ontology editor and knowledge acquisition system, current guidelines for ontology development, and tools for visual and linguistic presentation of the ontology.     

基于本体的分布式实例推理技术研究

为了克服单一实例库知识的局限性,实现分布式环境下多数据源的知识重用和共享,提出了一个分布式实例推理系统框架.系统通过本体服务器建立和维护实例库之间的本体知识,其中基本本体为知识的表示提供了全局约束和基础,实例推理服务器可以在基本本体框架下定义领域本体来灵活表达各自的领域知识,而本体目录则为知识的检索提供了向导.本体的引入解决了不同实例库之间知识的互理解和互操作性,能够有效地实现多实例库的协同推理.系统采用Web Service技术构建,是一个开放的系统框架,具有很强的可扩展性.     

Relating ontologies with a fuzzy information model

More people than ever before have access to information with the World Wide Web; information volume and number of users both continue to expand. Traditional search methods based on keywords are not effective, resulting in large lists of documents, many of which unrelated to users’ needs. One way to improve information retrieval is to associate meaning to users’ queries by using ontologies, knowledge bases that encode a set of concepts about one domain and their relationships. Encoding a knowledge base using one single ontology is usual, but a document collection can deal with different domains, each organized into an ontology. This work presents a novel way to represent and organize knowledge, from distinct domains, using multiple ontologies that can be related. The model allows the ontologies, as well as the relationships between concepts from distinct ontologies, to be represented independently. Additionally, fuzzy set theory techniques are employed to deal with knowledge subjectivity and uncertainty. This approach to organize knowledge and an associated query expansion method are integrated into a fuzzy model for information retrieval based on multi-related ontologies. The performance of a search engine using this model is compared with another fuzzy-based approach for information retrieval, and with the Apache Lucene search engine. Experimental results show that this model improves precision and recall measures.     

国家知识基础设施中的数学知识表示

数学知识表示是知识表示中的一个重要方面,是数学知识检索、自动定理机器证明、智能教学系统等的基础.根据在设计NKI(national knowledge infrastructure)的数学知识表示语言中遇到的问题,并在讨论了数学对象的本体论假设的基础上提出了两种数学知识的表示方法:一种是以一个逻辑语言上的公式为属性值域的描述逻辑;另一种是以描述逻辑描述的本体为逻辑语言的一部分的一阶逻辑.在前者的表示中,如果对公式不作任何限制,那么得到的知识库中的推理不是可算法化的;在后者的表示中,以描述逻辑描述的本体中的推理是可算法化的,而以本体为逻辑语言的一部分的一阶逻辑所表示的数学知识中的推理一般是不可算法化的.因此,在表示数学知识时,需要区分概念性的知识(本体中的知识)和非概念性的知识(用本体作为语言表示的知识).框架或者描述逻辑可以表示和有效地推理概念性知识,但如果将非概念性知识加入到框架或知识库中,就可能使得原来可以有效推理的框架所表示的知识库不存在有效的推理算法,甚至不存在推理算法.为此,建议在表示数学知识时,用框架或描述逻辑来表示概念性知识;然后,用这样表示的知识库作为逻辑语言的一部分,以表示非概念性知识.     

SEMANTICAL AND ONTOLOGICAL CONSIDERATIONS IN TELOS: A LANGUAGE FOR KNOWLEDGE REPRESENTATION DIMITRIS PLEXOUSAKIS

This paper focuses on the semantics of Telos, a language for representing knowledge about information systems. Telos is intended to support the development of information systems, especially in the requirements modeling phase. An object-oriented representational framework is supported by Telos. Its features include aggregation, generalization, and classification, the treatment of attributes as first-class objects and the explicit representation of time. Telos also provides an assertion sublanguage for expressing deductive rules and integrity constraints. A possible-worlds semantics is defined for Telos knowledge bases. This semantics is intended to capture the peculiarities involved in the interpretation of temporal expressions. The integration of time has also inspired the treatment of existence in Telos. An ontology of objects based on the property of existence is proposed. In the spirit of KRYPTON, Telos knowledge bases are specified functionally, in terms of the operations provided for querying and updating them. This knowledge-level analysis will allow us to specify exactly what a knowledge base can be ASK-ed or TELL-ed about the domain of discourse. Soundness, consistency, and completeness results have also been proven to complete the specification of Telos knowledge bases. This formal account of the language provides a logical framework that can be used to verify the correctness of any proposed implementation of the system.     

A knowledge encapsulation approach to ontology modularization

The development of monolithic ontologies for complex domains may face various challenges in reasoning and implementation. The notion of modularity can be employed for developing more efficient ontologies, especially in distributed environments. In this paper, we introduce a framework for developing ontologies in a modular manner. We describe the interface-based modular ontology formalism, (IBF), which theoretically supports the framework. The main feature of the framework is its support for knowledge encapsulation, i.e., it allows ontologies to define their main content using well-defined interfaces, such that their knowledge bases can only be accessed by other ontologies through these interfaces. An important implication of the proposed framework is that ontology modules can be developed completely independent of each other’s signature and languages. Such modules are free to only utilize the required knowledge segments of the others. We also investigate the issues of inconsistency in the proposed modular ontology framework. We provide solutions for isolating inconsistent ontology modules from the other parts of a modular ontology and also resolve inconsistencies which may be arisen by integrating consistent knowledge bases.     

Distributed fuzzy case based reasoning

This paper presents a framework for a distributed knowledge based system by integrating case based reasoning (CBR) and Fuzzy Logic. Fuzzy Logic gives CBR the power to deal with impreciseness and uncertainty. The framework for handling distributed case bases enables our system to construct solution based on collective experience distributed by discipline, time, and geography. In the proposed system the cases can be expressed in terms of attributes that can be crisp as well as fuzzy and appropriately similarity scores are computed. The cases can have attributes from a vocabulary, which can be defined with the constraint of global commitments so that the attributes can be shared and interpreted in a distributed setting. We have implemented a knowledge sharing protocol with common ontology as the repository of exchange vocabulary for knowledge sources with different Universe of Discourses (UOD). We have developed a shell for tailored application development in different domains. We have used RDBMS as the back end repository for cases, DAML + OIL for Ontology design, SAX and DOM for ontology access and RMI for remote procedure call. We have illustrated effectiveness of our approach by developing a travel planning and a help desk application.