基于本体的大规模定制产品配置模型

依据产品配置领域的相关知识,提出一种基于本体的大规模定制产品配置概念模型,其中包括配置类型和约束类。定义模型中每个概念及其关系,运用Web本体语言对其进行形式化的描述,使用语义Web规则语言表达特定的约束规则,基于Protégé对该模型进行有效性检验。     

An MDE-based methodology for closed-world integrity constraint checking in the semantic web

Ontology-based data-centric systems support open-world reasoning. Therefore, for these systems, Web Ontology Language (OWL) and Semantic Web Rule Language (SWRL) are not suitable for expressing integrity constraints based on the closed-world assumption. Thus, the requirement of integrating the open-world assumption of OWL/SWRL with closed-world integrity constraint checking is inevitable. SPARQL, recommended by World Wide Web (W3C), is a query language for RDF graphs, and many research studies have shown that it is a perfect candidate for closed-world constraint checking for ontology-based data-centric applications. In this regard, many research studies have been performed to transform integrity constraints into SPARQL queries where some studies have shown the limitations of partial expressivity of knowledge bases while performing the indirect transformations, whereas others are limited to a platform-specific implementation. To address these issues, this paper presents a flexible and formal methodology that employs Model-Driven Engineering (MDE) to model closed-world integrity constraints for open-world reasoning. The proposed approach offers semantic validation of data by expressing integrity constraints at both the model level and the code level. Moreover, straightforward transformations from OWL/SWRL to SPARQL can be performed. Finally, the methodology is demonstrated via a real-world case study of water observations data.     

Automatic extraction of OWL ontologies from UML class diagrams: a semantics-preserving approach

Full implementation of the Semantic Web requires widespread availability of OWL ontologies. Manual ontology development using current OWL editors remains a tedious and cumbersome task that requires significant understanding of the new ontology language and can easily result in a knowledge acquisition bottleneck. On the other hand, abundant domain knowledge has been specified by existing database schemata such as UML class diagrams. Thus developing an automatic tool for extracting OWL ontologies from existing UML class diagrams is helpful to Web ontology development. In this paper we propose an automatic, semantics-preserving approach for extracting OWL ontologies from existing UML class diagrams. This approach establishes a precise conceptual correspondence between UML and OWL through a semantics-preserving schema translation algorithm. The experiments with our implemented prototype tool, UML2OWL, show that the proposed approach is effective and a fully automatic ontology extraction is achievable. The proposed approach and tool will facilitate the development of Web ontologies and the realization of semantic interoperations between existing Web database applications and the Semantic Web.     

Bridging the gap between OWL and relational databases

Despite similarities between the Web Ontology Language (OWL) and schema languages traditionally used in relational databases, systems based on these languages exhibit quite different behavior in practice. The schema statements in relational databases are usually interpreted as integrity constraints and are used to check whether the data is structured according to the schema. OWL allows for axioms that resemble integrity constraints; however, these axioms are interpreted under the standard first-order semantics and not as checks. This often leads to confusion and is inappropriate in certain data-centric applications. To explain the source of this confusion, in this paper we compare OWL and relational databases w.r.t. their schema languages and basic computational problems. Based on this comparison, we extend OWL with integrity constraints that capture the intuition behind similar statements in relational databases. We show that, if the integrity constraints are satisfied, they need not be considered while answering a broad range of positive queries. Finally, we discuss several algorithms for checking integrity constraint satisfaction, each of which is suitable to different types of OWL knowledge bases.     

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。     

使用OWL DL形式化表达对象角色建模模型

对象角色建模(ORM)方法已应用于本体工程,因此需要将ORM模型转换为OWL DL公理,以便将ORM本体发布到语义Web上,同时还可使用支持DL的推理机来检查ORM本体的语义一致性和冗余问题。通过模型语义分析、模型等价转换、引入新的运算符和特性等方法,提出将ORM模型形式化表达为OWL DL公理的规则。除了外部唯一约束等四种约束外,其他形态的ORM模型都可以形式化表达为OWL DL公理。     

OWL DL的形式化基础研究

W3C正在制定的OWL DL是一种面向语义Web的知识表示标记语言，具有较强的知识表达能力并适合大规模应用的推理效率，是语义Web领域对适合语义Web应用的知识表示标记语言进行研究的最新综合．在知识表示领域，为了对知识表达能力和推理效率做合适的折衷，进行了大量关于描述逻辑的研究，本文以描述逻辑作为OWL DL的形式化基础，详细分析了OWL DL和描述逻辑间的对应关系，用描述逻辑的语义解释了OWL DL的各个基本元素，从而可以将描述逻辑领域研究的大量成果应用到OWL DL上来，为进一步研究OWL DL的知识表示、推理等问题奠定了基础．     

基于网络本体语言的三维计算机辅助设计主模型相似性计算方法

为了提高三维计算机辅助设计(CAD)模型重用效率,针对当前三维模型检索系统中语义表达不足问题,提出了一种基于网络本体语言(OWL)表示模型语义的相似性计算方法。首先,将三维CAD产品主模型转化成以概念属性特征为基础语义对象的结构化表示模型;然后,从OWL表示模型中提取用于评价两个模型相似性的特征语义信息,构建可量化的相似元集,借助子图同构思想和Tversky算法给出了一种加权相似性计算方法;最后,通过实例验证了所提方法的有效性和可行性。实验的定量评价结果表明,该评价基准从对象本身转为两个对象特性的语义描述,能够客观反映两对比模型的相似程度。     

基于语义的访问控制模型及其推理机制

对语义Web上资源进行访问要求授权决策充分考虑实体之间的语义关系,但传统的访问控制模型不能处理该问题。结合基于本体的语义描述技术和基于语义规则的推理机制,将不同的语义内部关系归纳为包含关系,提出一种面向语义Web的基于语义的访问控制模型,研究其语义授权推理机制,并提出一个推理实现系统。     

Identification and resolution of conflicts during ontological integration using rules

Abstract: Integration of ontologies of information sources and consumers is an important phase in achieving web‐based interoperability. The present work describes an approach for identifying certain semantic conflicts while integrating ontologies of heterogeneous information sources. This paper is focused on the identification of homonymy and synonymy between elements in ontologies. In the present work the concepts of homonymy and synonymy are synonymous to naming conflicts and entity identifier conflicts, respectively, and partial synonymy is synonymous to schema isomorphism conflicts. The concept of the mask of interoperability is introduced for the identification of synonymy. The mask of interoperability is expressed in a declarative way as a set of rules, which can then be used for resolution of conflicts during integration of ontologies. As proof of concept, ontologies are implemented using the XML‐based ontology language Ontology Web Language (OWL), and the rules are implemented using the emerging rule language Semantic Web Rule Language (SWRL). This representation in OWL and SWRL allows the ontology to be executable, flexibly extendable and platform‐independent. The OWL facts and SWRL rules are used by the Jess and Bossam reasoning engine to identify semantic homonymy and synonymy.     

基于OWL的自然灾害领域应急响应知识表示方法

利用语义网中本体和OWL(Ontology Web Language,即网络本体语言)等相关技术,通过一阶谓词逻辑及产生式知识表示方法具体描述地震灾害应急响应,为实现自然灾害领域应急响应的知识表示和共享提供一种参考。     

基于语义Web的受控自然语言系统推理模型

虽然相关研究组织提供了语义Web的一些简化工具,但是对不具备相关背景知识的领域专家来说,语义Web的可用性较低。提出了基于语义Web的受控自然语言系统推理模型,以解决这个问题。首先给出受控自然语言系统推理模型框架;然后分析受控自然语言的语言处理部分,提出基于WordNct的受控自然语言系统的本体词库模型和基于本体词库的受控自然语言解释器,把受控自然语言转换成中间表达语言篇章表述结构;最后通过推理部分把篇章表述结构转换成语义Web的本体和规则,通过模板工具映射成Jess的事实和规则,根据预定义的语义Web的公理和定理对受控自然语言进行推理。试验证明此模型大大提高了知识表示建模的效率,也基本满足简单推理任务,具有实用价值。     

Extending the Unified Modeling Language for ontology development

There is rapidly growing momentum for web enabled agents that reason about and dynamically integrate the appropriate knowledge and services at run-time. The dynamic integration of knowledge and services depends on the existence of explicit declarative semantic models (ontologies). We have been building tools for ontology development based on the Unified Modeling Language (UML). This allows the many mature UML tools, models and expertise to be applied to knowledge representation systems, not only for visualizing complex ontologies but also for managing the ontology development process. UML has many features, such as profiles, global modularity and extension mechanisms that are not generally available in most ontology languages. However, ontology languages have some features that UML does not support. Our paper identifies the similarities and differences (with examples) between UML and the ontology languages RDF and DAML+OIL. To reconcile these differences, we propose a modification to the UML metamodel to address some of the most problematic differences. One of these is the ontological concept variously called a property, relation or predicate. This notion corresponds to the UML concepts of association and attribute. In ontology languages properties are first-class modeling elements, but UML associations and attributes are not first-class. Our proposal is backward-compatible with existing UML models while enhancing its viability for ontology modeling. While we have focused on RDF and DAML+OIL in our research and development activities, the same issues apply to many of the knowledge representation languages. This is especially the case for semantic network and concept graph approaches to knowledge representations. Initial sbmission: 16 February 2002 / Revised submission: 15 October 2002 Published online: 2 December 2002