XSWRL,an Extended Semantic Web Rule Language and prototype implementation

Although the OWL (Web Ontology Language) and SWRL (Semantic Web Rule Language) add considerable expressiveness to the Semantic Web they do have expressive limitations. For some reasoning problems it is necessary to infer the existence of new individuals satisfying stated condition. This kind of problems can not be fully resolved by OWL and SWRL. We present the XSWRL (Extended Semantic Web Rule Language), an extension to SWRL, to overcome these problems. XSWRL introduces existentially quantified variables to rules. XSWRL extends SWRL in a syntactically and semantically coherent manner. We show that while the expressiveness of the Semantic Web language is improved, the undecidability and infinite chains are brought on. We define the inseparable set of atoms to separate XSWRL rules, and discuss a prototype implementation of reasoning support for XSWRL.     

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.     

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.     

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。     

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.     

Named graphs

The Semantic Web consists of many RDF graphs nameable by URIs. This paper extends the syntax and semantics of RDF to cover such named graphs. This enables RDF statements that describe graphs, which is beneficial in many Semantic Web application areas. Named graphs are given an abstract syntax, a formal semantics, an XML syntax, and a syntax based on N3. SPARQL is a query language applicable to named graphs. A specific application area discussed in detail is that of describing provenance information. This paper provides a formally defined framework suited to being a foundation for the Semantic Web trust layer.     

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。     

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.     

语义网中几种描述语言的比较研究

本体语言用于形式化描述Web文档中词汇的含义,在语义网中占有重要的位置。文中主要介绍了语义网的产生及其意义,并以语义网中描述语言的层次为出发点,比较了XML/XML Schema,RDF/RDF Schema及OWL（Ontology WebLanguage）的功能和作用。从描述语言表达能力的各个方面,比较这三种语言的关系和差异,并举出例子来说明OWL在语义网中的应用。     

语义网中几种描述语言的比较研究

本体语言用于形式化描述Web文档中词汇的含义,在语义网中占有重要的位置。文中主要介绍了语义网的产生及其意义,并以语义网中描述语言的层次为出发点,比较了XML/XML Schema,RDF/RDF Schema及OWL(Ontology WebLanguage)的功能和作用。从描述语言表达能力的各个方面,比较这三种语言的关系和差异,并举出例子来说明OWL在语义网中的应用。     

语义Web规则标记语言OWLRule+的设计与实现

语义Web是对未来Web体系结构的一个伟大设想，其研究分层次进行．目前足够成熟的最高层是以OWL语言为代表的ontology．但它的语义仅限于描述逻辑，该逻辑主要表示对象和类的层次结构，而规则的表达能力弱，因此在其之上需要一种表达力更丰富的逻辑语言．设计了一种新的语义Web规则标记语言OWLRule ：其语法扩展了OWL；语义基于CARIN，一种结合描述逻辑和Horn规则的表示语言；实现基于Jess规则推理机．实例学习展示了它对目前的Web ontology语言在规则表示和推理能力上的扩展．     

The Semantic Web: the roles of XML and RDF

XML and RDF are the current standards for establishing semantic interoperability on the Web, but XML addresses only document structure. RDF better facilitates interoperation because it provides a data model that can be extended to address sophisticated ontology representation techniques. We explain the role of ontologies in the architecture of the Semantic Web. We then briefly summarize key elements of XML and RDF, showing why using XML as a tool for semantic interoperability will be ineffective in the long run. We argue that a further representation and inference layer is needed on top of the Web's current layers, and to establish such a layer, we propose a general method for encoding ontology representation languages into RDF/RDF schema. We illustrate the extension method by applying it to Ontology Interchange Language, an ontology representation and inference language