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P2P网络中参与资源共享的节点日益增多,且呈海量趋势。如何在海量用户海量资源的情况下,查询整个P2P网络中的资源语义分布,计算网络中的所有语义聚类,是一个颇具挑战性的问题。针对这一问题,本文提出了一种面向自组织P2P网络的语义聚类查询算法SCQASPNSR。该算法可高效计算整个P2P网络中的语义聚类,为研究网络中资源语义分布、进行有效的知识发现,提供了有力支持。 相似文献
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Semantic interoperability between disparate systems in open, distributed environments has become the quest of many practitioners
in a variety of fields. One way to achieve such a goal is through ontology mapping. The perspective users of such technology,
however, are faced with a number of challenges including ambiguity of the meaning of mappings, difficulties of capturing semantics,
choice of the right ontology mapping tools, verification and validation of results and operationalisation in the beneficiary
semantic web application. In this paper we present a formalisation of ontologies and a triangle model for the ontology mapping
problems. This formalisation of ontology mapping reflects the engineering steps needed to materialise a versatile mapping
system in order to faithfully re-capture the semantics embodied in ontologies which is the fundamental requirements posed
by the semantic web environment. We further accommodate this formalisation with a series of specialist algorithms targeting
at particular aspects of semantic capturing. Finally, we evaluated the proposed algorithms by way of ontology mapping benchmark
tests. 相似文献
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P2P数据管理系统已经成为对等计算领域的研究重点。语义异构是P2P数据管理系统的首要问题。为了解决此问题,在每个数据源节点对共享的数据表的表名和属性名分别定义一系列关键字作为语义映射的媒介,具有相同关键字的异构数据源之间自动建立映射关系。这些关键字就形成了共享数据的外模式。但在节点内部,没有将外模式真正地物化为视图。定义好的关键字使用外模式描述文件分布到整个网络中。在查询的过程中,找到外模式描述文件后,立即将查询请求中的所有别名转换为真实的数据表名和属性名,从而既可以方便地按照任意名字找到需要的数据表,又可以减少数据备份的数量,简化查询算法,提高系统效率。 相似文献
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Shared ontologies describe concepts and relationships to resolve semantic conflicts amongst users accessing multiple autonomous and heterogeneous information sources. We contend that while ontologies are useful in semantic reconciliation, they do not guarantee correct classification of semantic conflicts, nor do they provide the capability to handle evolving semantics or a mechanism to support a dynamic reconciliation process. Their limitations are illustrated through a conceptual analysis of several prominent examples used in heterogeneous database systems and in natural language processing. We view semantic reconciliation as a nonmonotonic query-dependent process that requires flexible interpretation of query context, and as a mechanism to coordinate knowledge elicitation while constructing the query context. We propose a system that is based on these characteristics, namely the SCOPES (Semantic Coordinator Over Parallel Exploration Spaces) system. SCOPES takes advantage of ontologies to constrain exploration of a remote database during the incremental discovery and refinement of the context within which a query can be answered. It uses an Assumption-based Truth Maintenance System (ATMS) to manage the multiple plausible contexts which coexist while the semantic reconciliation process is unfolding, and the Dempster-Shafer (DS) theory of belief to model the likelihood of these plausible contexts. 相似文献
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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. 相似文献
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Deriving similarity for Semantic Web using similarity graph 总被引:1,自引:0,他引:1
JuHum Kwon O-Hoon Choi Chang-Joo Moon Soo-Hyun Park Doo-Kwon Baik 《Journal of Intelligent Information Systems》2006,26(2):149-166
One important research challenge of current Semantic Web is resolving the interoperability issue across ontologies. The issue
is directly related to identifying semantics of resources residing in different domain ontologies. That is, the semantics
of a concept in an ontology differs from others according to the modeling style and intuition of the knowledge expert even
though they are the same forms of a concept in each respective ontology. In this paper, we propose a similarity measure to
resolve the interoperability issue by using a similarity graph. The strong point of this paper is that we provide a precise
mapping technique and similarity properties to derive the similarity. The novel contribution of this paper is that we provide
a core technique of computing similarity across ontologies of Semantic Web.
This research was supported by the MIC (Ministry of Information and Communication), Korea, under the ITRC (Information Technology
Research Center) support program supervised by the IITA (Institute of Information Technology Assessment). 相似文献
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Vidal Martins Esther Pacitti Manal El Dick Ricardo Jimenez-Peris 《Distributed and Parallel Databases》2008,24(1-3):1-43
Collaborative applications are characterized by high levels of data sharing. Optimistic replication has been suggested as a mechanism to enable highly concurrent access to the shared data, whilst providing full application-defined consistency guarantees. Nowadays, there are a growing number of emerging cooperative applications adequate for Peer-to-Peer (P2P) networks. However, to enable the deployment of such applications in P2P networks, it is required a mechanism to deal with their high data sharing in dynamic, scalable and available way. Previous work on optimistic replication has mainly concentrated on centralized systems. Centralized approaches are inappropriate for a P2P setting due to their limited availability and vulnerability to failures and partitions from the network. In this paper, we focus on the design of a reconciliation algorithm designed to be deployed in large scale cooperative applications, such as P2P Wiki. The main contribution of this paper is a distributed reconciliation algorithm designed for P2P networks (P2P-reconciler). Other important contributions are: a basic cost model for computing communication costs in a DHT overlay network; a strategy for computing the cost of each reconciliation step taking into account the cost model; and an algorithm that dynamically selects the best nodes for each reconciliation step. Furthermore, since P2P networks are built independently of the underlying topology, which may cause high latencies and large overheads degrading performance, we also propose a topology-aware variant of our P2P-reconciler algorithm and show the important gains on using it. Our P2P-reconciler solution enables high levels of concurrency thanks to semantic reconciliation and yields high availability, excellent scalability, with acceptable performance and limited overhead. 相似文献
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Huayou Si Zhong Chen Yong Deng Lian Yu 《Service Oriented Computing and Applications》2013,7(3):169-180
Semantic web services (SWS) technology is developed to overcome the shortcomings of traditional standards, such as WSDL and UDDI, and enable maximal automation in all aspects of web service. But great improvement of capability in SWS-based service discovery is still desired. To address this issue, we present a distributed and semantic-matching-based approach for SWS publication and discovery by leveraging structured P2P technology. In this paper, first, we present our service matching rule which focuses on the inputs and outputs of SWS. Then, to realize this rule in open distributed environment and achieve the optimal match between a query and its qualified services, we propose not only a concept of ordered-concept-tree (OCT) to semantically sort the relevant concepts for service matching, but also a method to publish ontologies on structured P2P network to freely share and make full use of the concepts defined in different ontologies for OCT construction. Finally, we present a method for SWS publication on P2P network and an algorithm for service discovery. We also conduct experiments to evaluate our approach and the experimental results demonstrate its scalability, effectiveness, and callback capability to discover semantic web services. 相似文献
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目前的搜索引擎算法大多是基于关键词搜索,体系上是集中式结构,在安全性和语义性上存在缺陷.基于P2P的结构化半分布式语义搜索算法--DPSS(Distributed P2P Semantic Search),通过研究词与词的关联度,在传统的P2P覆盖语义层,实现语义功能.同时,结合文章距离算法,能够应用在文本分类、文章聚类等领域. 相似文献
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中文本体映射研究与实现 总被引:1,自引:0,他引:1
本体间的异构是语义网建设亟待解决的问题,本体映射则是解决本体异构的有效手段。中文资源是信息网络的重要组成部分,实现中文本体间以及中文与其他本体的映射是实现知识共享重用的一个重要组成部分。本文从元素层的角度对中文本体映射进行了研究,提出利用知网,结合多种技术计算词汇相似度,利用词汇的相似度计算概念匹配的可信度,实现元素层本体映射的算法,并根据此算法实现了ELOMC(Element Level Ontology Matching for Chinese)系统。 相似文献
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语义Web的高速发展使其具有动态性和异构性特征,解决语义信息的异构性问题成为实现信息集成的关键。本体作为一种语义Web的知识表示形式,增强了Web的语义信息。因此,为了解决语义异构性,实现数据间的互操作,必须建立异构本体间的映射关系。然而,为庞大的异构本体建立完全精确的本体映射是不现实的,本体映射中存在一定的不确定性。提出了一种新型的本体映射框架——语义集成中的不确定性本体映射。从不同方面研究本体特征,集合了多种映射策略,并引入了各映射策略中不确定性匹配的解决方案。实验证明,该方法具有可靠的实验性能,并且具有很好的通用性和可扩展性。 相似文献
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分布非结构化P2P网络资源定位研究 总被引:4,自引:0,他引:4
P2P系统是一个分布式系统,其中的资源如何进行定位是一个重要的问题。通过对分布非结构化P2P系统的搜索机制以及现有的改进方法的研究,给出了一种基于语义路由改进算法,并对此算法进行了模拟仿真。 相似文献
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路由算法在P2P网路中占有重要的地位,资源的定位、查找均依赖于高效的路由算法。传统的P2P网络采用分布式哈希表来进行路由,是与资源的自然语义内容无关的算法,或者说分布式哈希表破坏了自然语言的语义内容。最近10年以来,语义路由算法在P2P网络中逐渐兴起。随着语义网的提出,本体成为自然语言研究方面的热点。语义覆盖网正是基于本体的知识体系构建的。而随着社交网路的兴起,又提出了语义小世界的概念。LSI、LSH、VSM以及各中聚类算法均在P2P网络的语义路由中得到了广泛的应用。 相似文献
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Semantic-based searching in peer-to-peer (P2P) networks has drawn significant attention recently. A number of semantic searching schemes, such as GES proposed by Zhu Y et al., employ search models in Information Retrieval (IR). All these IR-based schemes use one vector to summarize semantic contents of all documents on a single node. For example, GES derives a node vector based on the IR model: VSM (Vector Space Model). A topology adaptation algorithm and a search protocol are then designed according to the similarity between node vectors of different nodes. Although the single semantic vector is suitable when the distribution of documents in each node is uniform, it may not be efficient when the distribution is diverse. When there are many categories of documents at each node, the node vector representation may be inaccurate. We extend the idea of GES and present a new class-based semantic searching scheme (CSS) specifically designed for unstructured P2P networks with heterogeneous single-node document collection. It makes use of a state-of-the-art data clustering algorithm, online spherical k-means clustering (OSKM), to cluster all documents on a node into several classes. Each class can be viewed as a virtual node. Virtual nodes are connected through virtual links. As a result, the class vector replaces the node vector and plays an important role in the class-based topology adaptation and search process. This makes CSS very efficient. Our simulation using the IR benchmark TREC collection demonstrates that CSS outperforms GES in terms of higher recall, higher precision, and lower search cost. 相似文献