Search (4 results, page 1 of 1)

0.03182815 = product of:
  0.0636563 = sum of:
    0.0636563 = product of:
      0.19096889 = sum of:
        0.19096889 = weight(_text_:3a in 701) [ClassicSimilarity], result of:
          0.19096889 = score(doc=701,freq=2.0), product of:
            0.50968707 = queryWeight, product of:
              8.478011 = idf(docFreq=24, maxDocs=44218)
              0.060118705 = queryNorm
            0.3746787 = fieldWeight in 701, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              8.478011 = idf(docFreq=24, maxDocs=44218)
              0.03125 = fieldNorm(doc=701)
      0.33333334 = coord(1/3)
  0.5 = coord(1/2)

Content

Vgl.: http%3A%2F%2Fdigbib.ubka.uni-karlsruhe.de%2Fvolltexte%2Fdocuments%2F1627&ei=tAtYUYrBNoHKtQb3l4GYBw&usg=AFQjCNHeaxKkKU3-u54LWxMNYGXaaDLCGw&sig2=8WykXWQoDKjDSdGtAakH2Q&bvm=bv.44442042,d.Yms.

0.012509546 = product of:
  0.025019092 = sum of:
    0.025019092 = product of:
      0.075057276 = sum of:
        0.075057276 = weight(_text_:objects in 2281) [ClassicSimilarity], result of:
          0.075057276 = score(doc=2281,freq=2.0), product of:
            0.3195352 = queryWeight, product of:
              5.315071 = idf(docFreq=590, maxDocs=44218)
              0.060118705 = queryNorm
            0.23489517 = fieldWeight in 2281, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              5.315071 = idf(docFreq=590, maxDocs=44218)
              0.03125 = fieldNorm(doc=2281)
      0.33333334 = coord(1/3)
  0.5 = coord(1/2)

Abstract

An information system like the Web is a continuously evolving system consisting of multiple heterogeneous information sources, covering a wide domain of discourse, and a huge number of users (human or software) with diverse characteristics and needs, that produce and consume information. The challenge nowadays is to build a scalable information infrastructure enabling the effective, accurate, content based retrieval of information, in a way that adapts to the characteristics and interests of the users. The aim of this work is to propose formally sound methods for building such an information network based on ontologies which are widely used and are easy to grasp by ordinary Web users. The main results of this work are: - A novel scheme for indexing and retrieving objects according to multiple aspects or facets. The proposed scheme is a faceted scheme enriched with a method for specifying the combinations of terms that are valid. We give a model-theoretic interpretation to this model and we provide mechanisms for inferring the valid combinations of terms. This inference service can be exploited for preventing errors during the indexing process, which is very important especially in the case where the indexing is done collaboratively by many users, and for deriving "complete" navigation trees suitable for browsing through the Web. The proposed scheme has several advantages over the hierarchical classification schemes currently employed by Web catalogs, namely, conceptual clarity (it is easier to understand), compactness (it takes less space), and scalability (the update operations can be formulated more easily and be performed more effciently). - A exible and effecient model for building mediators over ontology based information sources. The proposed mediators support several modes of query translation and evaluation which can accommodate various application needs and levels of answer quality. The proposed model can be used for providing users with customized views of Web catalogs. It can also complement the techniques for building mediators over relational sources so as to support approximate translation of partially ordered domain values.

0.011056981 = product of:
  0.022113962 = sum of:
    0.022113962 = product of:
      0.066341884 = sum of:
        0.066341884 = weight(_text_:objects in 3173) [ClassicSimilarity], result of:
          0.066341884 = score(doc=3173,freq=4.0), product of:
            0.3195352 = queryWeight, product of:
              5.315071 = idf(docFreq=590, maxDocs=44218)
              0.060118705 = queryNorm
            0.20761997 = fieldWeight in 3173, product of:
              2.0 = tf(freq=4.0), with freq of:
                4.0 = termFreq=4.0
              5.315071 = idf(docFreq=590, maxDocs=44218)
              0.01953125 = fieldNorm(doc=3173)
      0.33333334 = coord(1/3)
  0.5 = coord(1/2)

Abstract

The integration of metadata from distinct, heterogeneous data sources requires metadata interoperability, which is a qualitative property of metadata information objects that is not given by default. The technique of metadata mapping allows domain experts to establish metadata interoperability in a certain integration scenario. Mapping solutions, as a technical manifestation of this technique, are already available for the intensively studied domain of database system interoperability, but they rarely exist for the Web. If we consider the amount of steadily increasing structured metadata and corresponding metadata schemes on theWeb, we can observe a clear need for a mapping solution that can operate in aWeb-based environment. To achieve that, we first need to build its technical core, which is a mapping model that provides the language primitives to define mapping relationships. Existing SemanticWeb languages such as RDFS and OWL define some basic mapping elements (e.g., owl:equivalentProperty, owl:sameAs), but do not address the full spectrum of semantic and structural heterogeneities that can occur among distinct, incompatible metadata information objects. Furthermore, it is still unclear how to process defined mapping relationships during run-time in order to deliver metadata to the client in a uniform way. As the main contribution of this thesis, we present an abstract mapping model, which reflects the mapping problem on a generic level and provides the means for reconciling incompatible metadata. Instance transformation functions and URIs take a central role in that model. The former cover a broad spectrum of possible structural and semantic heterogeneities, while the latter bind the complete mapping model to the architecture of the Word Wide Web. On the concrete, language-specific level we present a binding of the abstract mapping model for the RDF Vocabulary Description Language (RDFS), which allows us to create mapping specifications among incompatible metadata schemes expressed in RDFS. The mapping model is embedded in a cyclic process that categorises the requirements a mapping solution should fulfil into four subsequent phases: mapping discovery, mapping representation, mapping execution, and mapping maintenance. In this thesis, we mainly focus on mapping representation and on the transformation of mapping specifications into executable SPARQL queries. For mapping discovery support, the model provides an interface for plugging-in schema and ontology matching algorithms. For mapping maintenance we introduce the concept of a simple, but effective mapping registry. Based on the mapping model, we propose aWeb-based mediator wrapper-architecture that allows domain experts to set up mediation endpoints that provide a uniform SPARQL query interface to a set of distributed metadata sources. The involved data sources are encapsulated by wrapper components that expose the contained metadata and the schema definitions on the Web and provide a SPARQL query interface to these metadata. In this thesis, we present the OAI2LOD Server, a wrapper component for integrating metadata that are accessible via the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). In a case study, we demonstrate how mappings can be created in aWeb environment and how our mediator wrapper architecture can easily be configured in order to integrate metadata from various heterogeneous data sources without the need to install any mapping solution or metadata integration solution in a local system environment.

0.010181569 = product of:
  0.020363137 = sum of:
    0.020363137 = product of:
      0.040726274 = sum of:
        0.040726274 = weight(_text_:22 in 642) [ClassicSimilarity], result of:
          0.040726274 = score(doc=642,freq=2.0), product of:
            0.21052547 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.060118705 = queryNorm
            0.19345059 = fieldWeight in 642, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.0390625 = fieldNorm(doc=642)
      0.5 = coord(1/2)
  0.5 = coord(1/2)

Date

22. 7.2022 12:16:58