OWL rules: A proposal and prototype implementation

Although the OWL Web Ontology Language adds considerable expressive power to the Semantic Web it does have expressive limitations, particularly with respect to what can be said about properties. We present the Semantic Web Rule Language (SWRL), a Horn clause rules extension to OWL that overcomes many of these limitations. SWRL extends OWL in a syntactically and semantically coherent manner: the basic syntax for SWRL rules is an extension of the abstract syntax for OWL DL and OWL Lite; SWRL rules are given formal meaning via an extension of the OWL DL model-theoretic semantics; SWRL rules are given an XML syntax based on the OWL XML presentation syntax; and a mapping from SWRL rules to RDF graphs is given based on the OWL RDF/XML exchange syntax. We discuss the expressive power of SWRL, showing that the ontology consistency problem is undecidable, provide several examples of SWRL usage, and discuss a prototype implementation of reasoning support for SWRL.     

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。     

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。     

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.     

基于语义网规则语言的推理机制框架设计

分析了本体描述语言OWL DL在表达能力上局限于描述逻辑的缺陷以及语义网规则语言(semantic web rule language,SWRL)的特点,在已有时本体和规则结合推理的研究基础上,提出了一个基于SWRL的推理机制框架.该框架在OWL本体中引入了规则的表示,弥补了OWLDL在推理机制上的不足,经该框架推导出的新本体在原本体的基础上增加了概念间的语义关联,将隐性知识显示化,完善了本体知识库的内容.在语义Web领域,该框架的应用能够提高本体知识的利用率.     

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。     

Ontology-based assembly design and information sharing for collaborative product development

To realize a truly collaborative product design and development process, effective communication among design collaborators is a must. In other words, the design intent that is imposed in a product design should be seized and interpreted properly; heterogeneous modeling terms should be semantically processed both by design collaborators and intelligent systems. Ontologies in the Semantic Web can explicitly represent semantics and promote integrated and consistent access to data and services. Thus, if an ontology is used in a heterogeneous and distributed design collaboration, it will explicitly and persistently represent engineering relations that are imposed in an assembly design. Design intent can be captured by reasoning, and, in turn, as reasoned facts, it can be propagated and shared with design collaborators. This paper presents a new paradigm of ontology-based assembly design. In the framework, an assembly design (AsD) ontology serves as a formal, explicit specification of assembly design so that it makes assembly knowledge both machine-interpretable and to be shared. An Assembly Relation Model (ARM) is enhanced using ontologies that represent engineering, spatial, assembly, and joining relations of assembly in a way that promotes collaborative assembly information-sharing environments. In the developed AsD ontology, implicit AsD constraints are explicitly represented using OWL (Web Ontology Language) and SWRL (Semantic Web Rule Language). This paper shows that the ability of the AsD ontology to be reasoned can capture both assembly and joining intents by a demonstration with a realistic mechanical assembly. Finally, this paper presents a new assembly design information-sharing framework and an assembly design browser for a collaborative product development.     

A hybrid ontology approach for integration of obsolescence information

Information sharing among distributed obsolescence management systems is a challenge because of the heterogeneity of data (data with different forms and representations). Indeed, this is the main hurdle that exists for current tools managing product obsolescence. This paper presents a hybrid ontology approach for the integration of obsolescence information that combines a global ontology that provides a shared vocabulary for the specification of the semantics of obsolescence domain knowledge, along with local ontologies that describe structures of multiple data sources distributed in various obsolescence management tools. A procedure is provided for mapping local ontologies to the global ontology by quantifying relationships between classes and identifying groups of classes with a clustering method. Ontologies and rules of identifying relationships are realized with OWL (Web Ontology Language) and SWRL (Semantic Web Rule Language). With the application of the hybrid ontology approach, a unified view of data is provided to support decision making for efficient obsolescence management and a structure where new sources of information can be easily added with little modification in the future.     

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.     

Ontology-based feature mapping and verification between CAD systems

Data interoperability between computer-aided design (CAD) systems remains a major obstacle in the information integration and exchange in a collaborative engineering environment. The use of CAD data exchange standards causes the loss of design intent such as construction history, features, parameters, and constraints, whereas existing research on feature-based data exchange only focuses on class-level feature definitions and does not support instance-level verification, which causes ambiguity in data exchange. In this paper, a hybrid ontology approach is proposed to allow for the full exchange of both feature definition semantics and geometric construction data. A shared base ontology is used to convey the most fundamental elements of CAD systems for geometry and topology, which is to both maximize flexibility and minimize information loss. A three-branch hybrid CAD feature model that includes feature operation information at the boundary representation level is constructed. Instance-level feature information in the form of the base ontology is then translated to local ontologies of individual CAD systems during the rule-based mapping and verification process. A combination of the Ontology Web Language (OWL) and Semantic Web Rule Language (SWRL) is used to represent feature classes and properties and automatically classify them by a reasoner in the target system, which requires no knowledge about the source system.     

Development of a product configuration system with an ontology-based approach

Product configuration is a crucial means to implement the mass customization paradigm by assembling a set of customizable components to satisfy both customers’ needs and technical constraints. With the aim of enabling efficient and effective development of product configuration systems by reusing configuration knowledge, an ontology-based approach to modeling product configuration knowledge is presented in this paper. The ontology-based product configuration models are hierarchically organized. At the lower level, a configuration meta-model is defined. Based on this meta-model, domain-specific configuration knowledge can be derived by reusing or inheriting the classes or relations in the meta-model. Configuration models are formalized using OWL (Ontology Web Language), an ontology representation language developed by W3C. As a result, configuration models have well-defined semantics due to the logic semantics of OWL, making it possible to automatically detect inconsistencies of configuration knowledge bases. Furthermore, configuration constraints are represented in SWRL, a rule language based on OWL. Finally, actual configuration processes are carried out using JESS, a rule engine for the Java platform, by mapping OWL-based configuration facts and SWRL-based configuration constraints into JESS facts and JESS rules, respectively. The proposed methodology is illustrated with an example for configuring the ranger drilling machine.     

Interpreting SWRL Rules in RDF Graphs

An unresolved issue in SWRL (the Semantic Web Rule Language) is whether the intended semantics of its RDF representation can be described as an extension of the W3C RDF semantics. In this paper we propose to make the model-theoretic semantics of SWRL compatible with RDF by interpreting SWRL rules in RDF graphs. For dealing with SWRL/RDF rules, we regard ‘Implies’ as an OWL class, and extract all ‘Implies’ rules from an RDF database that represents a SWRL knowledge base. Each ‘Implies’ rule is grounded through mappings built into the semantic conditions of the model theory. Based on the fixpoint semantics, a bottom-up strategy is employed to compute the least Herbrand models.     

A Flexible Ontology Reasoning Architecture for the Semantic Web

Knowledge-based systems in the semantic Web era can make use of the power of the semantic Web languages and technologies, in particular those related to ontologies. Recent research has shown that user-defined data types are very useful for semantic Web and ontology applications. The W3C semantic Web best practices and development working group has set up a task force to address this issue. Very recently, OWL-Eu and OWL-E, two decidable extensions of the W3C standard ontology language OWL DL, have been proposed to support customized data types and customized data type predicates, respectively. In this paper, we propose a flexible reasoning architecture for these two expressive semantic Web ontology languages and describe our prototype implementation of the reasoning architecture, based on the well-known FaCT DL reasoner, which witnesses the two key flexibility features of our proposed architecture: 1) It allows users to define their own data types and data type predicates based on built-in ones and 2) new data type reasoners can be added into the architecture without having to change the concept reasoner     

权限扩展RBAC模型的本体表示和实现

针对基于角色的访问控制(RBAC)模型对权限实体的刻画能力不足,提出了带权限层次扩展的RBAC模型。为结合本体在知识表示和推理方面的优势,提出了该模型的本体表示和实现方法。该方法使用Web本体语言(OWL)表示该扩展模型,借助语义Web规则语言(SWRL)定义模型中应用逻辑规则,隐式授权知识经规则推理获得。在此基础上,通过SPARQL协议和RDF查询语言(SPARQL)查询命令生成显式和隐式授权视图,实现系统安全状态分析。最后,给出了具体应用示例,表明该方法的可行性。     

故障树领域本体及SWRL规则的构建方法研究

故障树(Fault Tree,FT)被广泛应用于系统故障的快速定位,但其因缺乏精确的语义信息而存在重复构建问题。将本体引入到故障树领域中,并对如何构建故障树本体及相应的SWRL规则进行了研究:首先采用本体描述语言 (Web Ontology Language,OWL)对故障树中的概念及概念之间的关系进行知识表示,构建了一个可共享、可重用、可扩展的故障树领域本体;然后将故障树中事件之间的逻辑关系转化成语义 Web 规则语言 (Semantic Web Rule Language,SWRL);最后将构建的故障树领域本体和SWRL规则放入JESS推理机中进行推理,产生新的知识,用于系统故障的快速定位。实验证明,使用所提出的方法能在解决故障树重复构建问题的同时,不对系统故障的快速定位产生影响。     

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。     

Clustering rule bases using ontology-based similarity measures

Rules are increasingly becoming an important form of knowledge representation on the Semantic Web. There are currently few methods that can ensure that the acquisition and management of rules can scale to the size of the Web. We previously developed methods to help manage large rule bases using syntactical analyses of rules. This approach did not incorporate semantics. As a result, rule categorization based on syntactic features may not be effective. In this paper, we present a novel approach for grouping rules based on whether the rule elements share relationships within a domain ontology. We have developed our method for rules specified in the Semantic Web Rule Language (SWRL), which is based on the Web Ontology Language (OWL) and shares its formal underpinnings. Our method uses vector space modeling of rule atoms and an ontology-based semantic similarity measure. We apply a clustering method to detect rule relatedness, and we use a statistical model selection method to find the optimal number of clusters within a rule base. Using three different SWRL rule bases, we evaluated the results of our semantic clustering method against those of our syntactic approach. We have found that our new approach creates clusters that better match the rule bases’ logical structures. Semantic clustering of rule bases may help users to more rapidly comprehend, acquire, and manage the growing numbers of rules on the Semantic Web.     

基于本体的语义Web服务QoS描述和发现

WS-QMO是提出的一个用来对Web服务及其QoS信息进行建模和发现的顶层本体,它既可用于对服务QoS信息的描述和发布,也可用于对服务QoS需求的描述.WS-QMO本体基本满足了当前对Web服务QoS语义建模的普遍要求,并且由于适当地加入SWRL规则,它不但可以灵活地自定义单个QoS属性,描述一个QoS属性在不同条件下的不同取值,还可以定义复杂的组合QoS属性.相对同类本体或描述语言,它能更好地描述具有复杂约束规则的QoS属性,同时尽量利用现有的成熟规范使其定义式更为简洁.最后给出了基于该本体的QoS知识库的管理方法以及一个新的自动服务发现算法,该算法仅使用描述逻辑推理机的功能便可实现复杂约束的QoS自动服务发现,使得基于WS-QMO的Web服务建模和发现同时具备较好的描述能力和执行效率.