895 resultados para Semantic web


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随着Internet上异构应用系统的大量增加和SOA技术的空前发展,Web服务技术变得越来越重要,已经成为了学术界和工业界关注的热点。在Web服务技术中,服务发现为Web服务消费者调用Web服务提供者提供的服务提供了桥梁,起到非常重要的承接作用,成为了Web服务技术中的重点。目前的Web服务发现机制主要有两种,第一种是传统的Web服务发现方式,主要基于UDDI(Universal Description, Discovery and Integration)的纯粹关键字查找;第二种是基于Web服务的语义信息,进行Web服务间的语义匹配。 第一种方法的基础UDDI是国际标准,而且应用也最为广泛,但UDDI中对于Web服务的描述是基于语法的,而且缺乏Web服务所特有的I/O属性和服务质量属性等信息。第二种方法基于Web服务的语义信息,包括Web服务所特有的I/O属性,但因为缺乏灵活有效的Web服务匹配方法和与之对应的Web服务匹配框架,限制了其应用。 基于此,本文在对当前语义Web服务匹配技术分析和研究的基础上,对当前的语义Web服务匹配方法进行了改进,同时提出了基于过滤器(filter)的语义Web服务匹配框架模型。本文的主要工作有: 1)对目前的语义Web服务匹配技术进行了较为全面深入的探讨和综述。 2)对当前的语义Web服务匹配的各个阶段进行了详细的分析,对其中的匹配方法进行了改进。提出了基于向量空间模型(VSM)和TF-IDF(Term Frequency–Inverse Document Frequency)思想的本体权重的计算方法,本体层次关系图中边的权重的计算方法和本体之间相似度的计算方法。 3)提出了基于web服务黑盒属性的语义。 4)语义Web服务匹配框架方面,本文提出了基于filter的语义Web服务匹配框架,并将其延伸到非语义Web服务系统中。

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语义Web是现有Web的一个语义延伸,目标是使Web的应用具有一定的智能,能够进行更准确的信息搜索和一定的决策支持,帮助用户自动完成一些任务。语义Web的实现需要人工智能、数据库等领域的技术支持,需要对已有的技术进行改进和扩展,也需要对现有技术本身如ECA规则进行更深入的研究从而进一步将其扩展到语义Web。自动推理技术是语义Web实现的基础之一,而ECA规则可以为系统增加反应性行为能力,本文围绕自动推理和ECA规则,主要进行了如下研究:(1) 一阶逻辑推理技术对语义Web的推理支持。分析了语义Web语言需要的表达能力,对现有描述逻辑工具、一阶逻辑工具的能力进行了考察。现有的描述逻辑工具不足以处理应用所需要的更丰富的语言成分、任意的一阶逻辑规则等,而一阶逻辑自动定理证明工具和有限模型查找工具有分别都有较好的研究成果。把语义Web的推理问题化成可满足性判定问题后,本文给出了一阶逻辑定理证明器和有限模型查找器形成的并发过程进行可满足性判定的方法。这样既可以解决描述逻辑工具的不足,并可弥补定理证明器对可满足的公式推理的不完备性。(2) ECA规则(主动规则)的终止性分析。终止性是主动规则最重要的行为性质,不终止是由于主动规则的级联触发造成的,意味着定义错误。终止性检查通常是不可判定的。有效的静态分析方法是主动规则得以实际应用的保证。静态分析的关键是合适的数据库状态描述,本文给出用约束表示数据库状态的方法,通过模拟规则执行,使用约束求解进行条件计算和重复状态检查,判断主动规则集合是否终止。用约束精确表示了数据库状态,在规则处理中考虑了执行语义,从而得到更精确的终止性结论。

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语义WebWeb服务是当前热门的应用技术,而两者的结合——语义Web服务将在未来几年具有极大的应用前景。语义使得~Web~服务的自动发现和自动组装变得非常容易、高效,但是随之而来的问题是如何确保自动组装的~Web~服务组合在本体知识库的状态下是一致的,并且在执行过程中也始终保持一致。 本文介绍了一种基于路径的语义Web服务组合验证方案,通过对服务组合中的单个Web服务进行输入、输出、前置条件和执行效果(IOPE)进行语义标注,旨在找出组合执行过程中在任何结点处可能存在的不一致性。文章定义了显式不一致性和隐式不一致性,首先提出了语义Web服务前置条件和执行效果的正规化表示方法,然后介绍了顺序和并发执行的多个Web服务之执行效果自动化累积算法,接下来给出了基于路径的一致性验证算法。文章还给出了实现该验证方案的平台架构,给出了相关实验过程和结果。 文章还完整地介绍了中科院某研究所本体的构造和扩充过程,定义了研究生毕业申请服务组合,并介绍了服务的IOPE标注,最后运用验证方案对该组合进行验证,给出了验证结果。

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Se analizan y describen las principales líneas de trabajo de la Web Semántica en el ámbito de los archivos de televisión. Para ello, se analiza y contextualiza la web semántica desde una perspectiva general para posteriormente analizar las principales iniciativas que trabajan con lo audiovisual: Proyecto MuNCH, Proyecto S5T, Semantic Television y VideoActive.

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Dans cette thèse, nous présentons les problèmes d’échange de documents d'affaires et proposons une méthode pour y remédier. Nous proposons une méthodologie pour adapter les standards d’affaires basés sur XML aux technologies du Web sémantique en utilisant la transformation des documents définis en DTD ou XML Schema vers une représentation ontologique en OWL 2. Ensuite, nous proposons une approche basée sur l'analyse formelle de concept pour regrouper les classes de l'ontologie partageant une certaine sémantique dans le but d'améliorer la qualité, la lisibilité et la représentation de l'ontologie. Enfin, nous proposons l’alignement d'ontologies pour déterminer les liens sémantiques entre les ontologies d'affaires hétérogènes générés par le processus de transformation pour aider les entreprises à communiquer fructueusement.

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This report gives a detailed discussion on the system, algorithms, and techniques that we have applied in order to solve the Web Service Challenges (WSC) of the years 2006 and 2007. These international contests are focused on semantic web service composition. In each challenge of the contests, a repository of web services is given. The input and output parameters of the services in the repository are annotated with semantic concepts. A query to a semantic composition engine contains a set of available input concepts and a set of wanted output concepts. In order to employ an offered service for a requested role, the concepts of the input parameters of the offered operations must be more general than requested (contravariance). In contrast, the concepts of the output parameters of the offered service must be more specific than requested (covariance). The engine should respond to a query by providing a valid composition as fast as possible. We discuss three different methods for web service composition: an uninformed search in form of an IDDFS algorithm, a greedy informed search based on heuristic functions, and a multi-objective genetic algorithm.

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A key argument for modeling knowledge in ontologies is the easy re-use and re-engineering of the knowledge. However, beside consistency checking, current ontology engineering tools provide only basic functionalities for analyzing ontologies. Since ontologies can be considered as (labeled, directed) graphs, graph analysis techniques are a suitable answer for this need. Graph analysis has been performed by sociologists for over 60 years, and resulted in the vivid research area of Social Network Analysis (SNA). While social network structures in general currently receive high attention in the Semantic Web community, there are only very few SNA applications up to now, and virtually none for analyzing the structure of ontologies. We illustrate in this paper the benefits of applying SNA to ontologies and the Semantic Web, and discuss which research topics arise on the edge between the two areas. In particular, we discuss how different notions of centrality describe the core content and structure of an ontology. From the rather simple notion of degree centrality over betweenness centrality to the more complex eigenvector centrality based on Hermitian matrices, we illustrate the insights these measures provide on two ontologies, which are different in purpose, scope, and size.

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Lecture 4: Ontological Hypertext and the Semantic Web Contains Powerpoint Lecture slides and Hypertext Research Papers: Conceptual linking: Ontology-based Open Hypermedia (Carr et al. 2001); CS AKTiveSpace: Building a Semantic Web Application (Glaser et al., 2004); The Semantic Web Revisited (Shadbolt, Hall and Berners-Lee, 2006); Mind the Semantic Gap (Millard et al., 2005).

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In this class, we will discuss metadata as well as current phenomena such as tagging and folksonomies. Readings: Ontologies Are Us: A Unified Model of Social Networks and Semantics, P. Mika, International Semantic Web Conference, 522-536, 2005. [Web link] Optional: Folksonomies: power to the people, E. Quintarelli, ISKO Italy-UniMIB Meeting, (2005)

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A resource for the teaching of concepts involved in 'web 3.0', including a powerpoint presentation with quiz, and accompanying tutorial

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Wednesday 2nd April 2014 Speaker(s): Stefan Decker Time: 02/04/2014 11:00-11:50 Location: B2/1083 File size: 897 Mb Abstract Ontologies have been promoted and used for knowledge sharing. Several models for representing ontologies have been developed in the Knowledge Representation field, in particular associated with the Semantic Web. In my talk I will summarise developments so far, and will argue that the currently advocated approaches miss certain basic properties of current distributed information sharing infrastructures (read: the Web and the Internet). I will sketch an alternative model aiming to support knowledge sharing and re-use on a global basis.