语义Web中的本体推理研究

从语义Web的基本概念开始,介绍了语义Web的层次结构;介绍了本体的基本概念以及用于本体描述的几种语言。用W3C推荐的本体描述语言OWL描述了一个本体实例,通过此实例对本体推理在本体建立中的冲突消解、描述优化、本体的合并和实例归类中的应用进行了研究,说明了本体推理在本体建立及本体应用中的作用。本体技术是语义Web的核心技术,所以建立和维护本体是语义Web中的主要工作之一,而基于本体的推理可以帮助建立和维护本体。     

一种基于语义的协同工作模型

针对产品制造领域,提出一种基于语义的协同工作模型。该模型分别以XML和RDF(S)作为协同信息的语法描述模式和语义描述模型,为协同信息提供机器呵处理和可理解能力;通过建立由个体Ontology和顶层Ontology构成的两层Ontology体系,以个体Ontology描述协同过程中个人或团体的领域背景知识,以顶层Ontology为概念和语义参照模型,建立协同信息之间的语义约束,为协同过程提供多领域知识共享和互操作环境。     

Semantic Ontology Mapping for Interoperability of Learning Resource Systems using a rule-based reasoning approach

There is an increasing demand for sharing learning resources between existing learning resource systems to support reusability, exchangeability, and adaptability. The learning resources need to be annotated with ontologies into learning objects that use different metadata standards. These ontologies have introduced the problems of semantic and structural heterogeneity. This research proposes a Semantic Ontology Mapping for Interoperability of Learning Resource Systems. To enable semantic ontology mapping, this research proposes conflict detection and resolution techniques for both semantic and structural conflicts. The Semantic Bridge Ontology has been proposed as a core component for generating mapping rules to reconcile terms defined in local ontologies into terms defined in the target common ontology. This work defines the reasoning rules to classify related learning objects to enhance the powerful deductive reasoning capabilities of the system. As a consequence, ontology-based learning object metadata are generated and used by the semantic query engine to facilitate user queries of learning objects across heterogeneous learning resource systems.     

Ontology selection ranking model for knowledge reuse

Ontology reuse is recommended as a key factor to develop cost-effective and high-quality ontologies because it could reduce development costs by avoiding rebuilding existing ontologies. Selecting the desired ontology from existing ontologies is essential for ontology reuse. Until now, much research on ontology selection has focused on lexical-level support. However, in these cases, it is almost impossible to find an ontology that includes all the concepts matched by the search terms at the semantic level. Finding an ontology that meets users’ needs requires a new ontology selection and ranking mechanism based on semantic similarity matching. We propose an ontology selection and ranking model consisting of selection standards and metrics based on better semantic matching capabilities. The model we propose presents two novel features different from previous research models. First, it enhances the ontology selection and ranking method practically and effectively by enabling semantic matching of taxonomy or relational linkage between concepts. Second, it identifies what measures should be used to rank ontologies in the given context and what weight should be assigned to each selection measure.     

MOVE: A Distributed Framework for Materialized Ontology View Extraction

The use of ontologies lies at the very heart of the newly emerging era of semantic web. Ontologies provide a shared conceptualization of some domain that may be communicated between people and application systems. As information on the web increases significantly in size, web ontologies also tend to grow bigger, to such an extent that they become too large to be used in their entirety by any single application. Moreover, because of the size of the original ontology, the process of repeatedly iterating the millions of nodes and relationships to form an optimized sub-ontology becomes very computationally extensive. Therefore, it is imperative that parallel and distributed computing techniques be utilized to implement the extraction process. These problems have stimulated our work in the area of sub-ontology extraction where each user may extract optimized sub-ontologies from an existing base ontology. The extraction process consists of a number of independent optimization schemes that cover various aspects of the optimization process, such as ensuring consistency of the user-specified requirements for the sub-ontology, ensuring semantic completeness of the sub-ontology, etc. Sub-ontologies are valid independent ontologies, known as materialized ontologies, that are specifically extracted to meet certain needs. Our proposed and implemented framework for the extraction process, referred to as Materialized Ontology View Extractor (MOVE), has addressed this problem by proposing a distributed architecture for the extraction/optimization of a sub-ontology from a large-scale base ontology. We utilize coarse-grained data-level parallelism inherent in the problem domain. Such an architecture serves two purposes: (a) facilitates the utilization of a cluster environment typical in business organizations, which is in line with our envisaged application of the proposed system, and (b) enhances the performance of the computationally extensive extraction process when dealing with massively sized realistic ontologies. As ontologies are currently widely used, our proposed approach for distributed ontology extraction will play an important role in improving the efficiency of ontology-based information retrieval.     

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.     

A semantic similarity method based on information content exploiting multiple ontologies

The quantification of the semantic similarity between terms is an important research area that configures a valuable tool for text understanding. Among the different paradigms used by related works to compute semantic similarity, in recent years, information theoretic approaches have shown promising results by computing the information content (IC) of concepts from the knowledge provided by ontologies. These approaches, however, are hampered by the coverage offered by the single input ontology. In this paper, we propose extending IC-based similarity measures by considering multiple ontologies in an integrated way. Several strategies are proposed according to which ontology the evaluated terms belong. Our proposal has been evaluated by means of a widely used benchmark of medical terms and MeSH and SNOMED CT as ontologies. Results show an improvement in the similarity assessment accuracy when multiple ontologies are considered.     

基于本体映射的多本体查询方法

随着语义网的发展,本体已经成为很多领域表达知识的主要手段。许多领域都根据自己的需求建立了本体来描述本领域内的知识。但是目前许多针对本体的语义查询只能对一个本体进行查询。为了实现一个查询能够对多个本体进行访问并且返回适当的查询结果,文中提出了一种利用本体映射实现对多本体的查询方法。其中的映射方法是一种基于语义的多策略结合方式。通过实验发现查询的速度与本体的数量基本呈线性关系且不会因为本体异构程度而增加。     

Enabling Cross-Disciplinary E-Science by Integrating Geoscience Ontologies with Dolce

E-Science is increasingly being used to address scientific problems that require cross-disciplinary knowledge, such as climate change, natural disasters, and environmental health. However, the ontologies used to represent scientific knowledge are largely unidisciplinary and need to be integrated to enable big e-Science. The authors investigate the potential of the Dolce foundational ontology to aid the integration of two geoscientific knowledge representations, the Sweet ontology and the GeoSciML schema, to meet the requirements of a cross-disciplinary use case focused on groundwater pollution estimation. They connected the domain ontologies via the foundational ontology, leading to new and improved relations between the domain ontologies that enabled satisfaction of the use case. Although the integrated ontology, called Dolce Rocks, contains some semantic inconsistencies resulting from incompatibilities among the ontologies, the overall results suggest that foundational ontologies can play an important role in cross-disciplinary e-Science.     

基于匿名消息广播的电子选举方案

针对目前基于语义网的本体映射算法中背景本体搜索面少、本体收集不精确的问题,利用基于虚拟文档的映射技术提取在Word-Net中与概念同义的同义词集,将对单个概念进行搜索转换成对同义概念集进行搜索,从而扩大本体搜索面,获取更多背景本体.提出基于语义环境的动态本体映射算法来排除错误背景本体,使本体收集更加精确.实验结果表明,该算法可有效提高映射的查全率和查准率.     

一种面向语义网服务的本体映射框架*

本体的异构性阻碍了语义网服务的互操作。从解决语义网服务中本体的异构问题出发,同时考虑到目前的本体映射系统大多效率不高、映射结果不够准确的问题,提出了一种适用于语义网服务的本体映射方法及系统框架。该方法利用机器学习技术来提高本体映射的自动化程度,利用综合评判技术修正映射结果,以提高本体映射的准确率。采用OAEI 2007的基准测试数据集benchmarks进行实验测试,结果表明本系统的性能基本达到预期效果,能够有效地解决语义网服务中的本体异构问题。     

一种基于语义网的本体映射改进算法

针对目前基于语义网的本体映射算法中背景本体搜索面少、本体收集不精确的问题,利用基于虚拟文档的映射技术提取在Word—Net中与概念同义的同义词集,将对单个概念进行搜索转换成对同义概念集进行搜索,从而扩大本体搜索面,获取更多背景本体。提出基于语义环境的动态本体映射算法来排除错误背景本体,使本体收集更加精确。实验结果表明,该算法可有效提高映射的查全率和查准率。     

A semantic metrics suite for evaluating modular ontologies

Ontologies, which are formal representations of knowledge within a domain, can be used for designing and sharing conceptual models of enterprises information for the purpose of enhancing understanding, communication and interoperability. For representing a body of knowledge, different ontologies may be designed. Recently, designing ontologies in a modular manner has emerged for achieving better reasoning performance, more efficient ontology management and change handling. One of the important challenges in the employment of ontologies and modular ontologies in modeling information within enterprises is the evaluation of the suitability of an ontology for a domain and the performance of inference operations over it. In this paper, we present a set of semantic metrics for evaluating ontologies and modular ontologies. These metrics measure cohesion and coupling of ontologies, which are two important notions in the process of assessing ontologies for enterprise modeling. The proposed metrics are based on semantic-based definitions of relativeness, and dependencies between local symbols, and also between local and external symbols of ontologies. Based on these semantic definitions, not only the explicitly asserted knowledge in ontologies but also the implied knowledge, which is derived through inference, is considered for the sake of ontology assessment. We present several empirical case studies for investigating the correlation between the proposed metrics and reasoning performance, which is an important issue in applicability of employing ontologies in real-world information systems.     

Axiom-based ontology matching

Abstract: Managing multiple ontologies is now a core question in most of the applications that require semantic interoperability. The semantic web is surely the most significant application of this report: the current challenge is not to design, develop and deploy domain ontologies but to define semantic correspondences among multiple ontologies covering overlapping domains. In this paper, we introduce a new approach of ontology matching named axiom-based ontology matching. As this approach is founded on the use of axioms, it is mainly dedicated to heavyweight ontologies, but it can also be applied to lightweight ontologies as a complementary approach to the current techniques based on the analysis of natural language expressions, instances and/or taxonomical structures of ontologies. This new matching paradigm is defined in the context of the conceptual graphs model, where the projection (i.e. the main operator for reasoning with conceptual graphs which corresponds to homomorphism of graphs) is used as a means to semantically match the concepts and the relations of two ontologies through the explicit representation of the axioms in terms of conceptual graphs. We also introduce an ontology of representation, called MetaOCGL, dedicated to the reasoning of heavyweight ontologies at the meta-level.     

面向模块重用的描述逻辑SHJF本地性规则研究

可重用本体模块的抽取是本体重用的一个关键环节。与传统工程应用中使用的基于本体层次的结构化方法抽取本体模块相比,使用逻辑的方法能充分利用本体提供的语义信息,抽取的本体模块更具完整性和正确性。在研究保守扩展的本体模块理论基础上,根据Grau B C提出的 SHOJQ 本地性规则,提出并证明了描述逻辑SHJF对应的语义本地性规则和句法本地性规则,为基于该规则抽取可重用本体模块提供了理论基础。     

BiOSS: A system for biomedical ontology selection

In biomedical informatics, ontologies are considered a key technology for annotating, retrieving and sharing the huge volume of publicly available data. Due to the increasing amount, complexity and variety of existing biomedical ontologies, choosing the ones to be used in a semantic annotation problem or to design a specific application is a difficult task. As a consequence, the design of approaches and tools addressed to facilitate the selection of biomedical ontologies is becoming a priority. In this paper we present BiOSS, a novel system for the selection of biomedical ontologies. BiOSS evaluates the adequacy of an ontology to a given domain according to three different criteria: (1) the extent to which the ontology covers the domain; (2) the semantic richness of the ontology in the domain; (3) the popularity of the ontology in the biomedical community. BiOSS has been applied to 5 representative problems of ontology selection. It also has been compared to existing methods and tools. Results are promising and show the usefulness of BiOSS to solve real-world ontology selection problems. BiOSS is openly available both as a web tool and a web service.     

Measuring Concept Similarities in Multimedia Ontologies: Analysis and Evaluations

The recent development of large-scale multimedia concept ontologies has provided a new momentum for research in the semantic analysis of multimedia repositories. Different methods for generic concept detection have been extensively studied, but the question of how to exploit the structure of a multimedia ontology and existing inter-concept relations has not received similar attention. In this paper, we present a clustering-based method for modeling semantic concepts on low-level feature spaces and study the evaluation of the quality of such models with entropy-based methods. We cover a variety of methods for assessing the similarity of different concepts in a multimedia ontology. We study three ontologies and apply the proposed techniques in experiments involving the visual and semantic similarities, manual annotation of video, and concept detection. The results show that modeling inter-concept relations can provide a promising resource for many different application areas in semantic multimedia processing.     

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.     

Ontology versioning in an ontology management framework

Ontologies have become ubiquitous in information systems. They constitute the semantic Web's backbone, facilitate e-commerce, and serve such diverse application fields as bioinformatics and medicine. As ontology development becomes increasingly widespread and collaborative, developers are creating ontologies using different tools and different languages. These ontologies cover unrelated or overlapping domains at different levels of detail and granularity. A uniform framework, which we present here, helps users manage multiple ontologies by leveraging data and algorithms developed for one tool in another. For example, by using an algorithm we developed for structural evaluation of ontology versions, this framework lets developers compare different ontologies and map similarities and differences among them. Multiple-ontology management includes these tasks: maintain ontology libraries, import and reuse ontologies, translate ontologies from one formalism to another, support ontology versioning, specify transformation rules between different ontologies and version, merge ontologies, align and map between ontologies, extract an ontology's self-contained parts, support inference across multiple ontologies, support query across multiple ontologies.