Search (50 results, page 3 of 3)

0.0045745755 = product of:
  0.018298302 = sum of:
    0.018298302 = product of:
      0.036596604 = sum of:
        0.036596604 = weight(_text_:aspects in 127) [ClassicSimilarity], result of:
          0.036596604 = score(doc=127,freq=2.0), product of:
            0.20938325 = queryWeight, product of:
              4.5198684 = idf(docFreq=1308, maxDocs=44218)
              0.046325076 = queryNorm
            0.17478286 = fieldWeight in 127, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              4.5198684 = idf(docFreq=1308, maxDocs=44218)
              0.02734375 = fieldNorm(doc=127)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Abstract

This thesis is organised as follows: Chapter 2 gives a general introduction to the field of information retrieval, covering its most important aspects. Further, the tasks of distributed and peer-to-peer information retrieval (P2PIR) are introduced, motivating their application and characterising the special challenges that they involve, including a review of existing architectures and search protocols in P2PIR. Finally, chapter 2 presents approaches to evaluating the e ectiveness of both traditional and peer-to-peer IR systems. Chapter 3 contains a detailed account of state-of-the-art information retrieval models and algorithms. This encompasses models for matching queries against document representations, term weighting algorithms, approaches to feedback and associative retrieval as well as distributed retrieval. It thus defines important terminology for the following chapters. The notion of "multi-level association graphs" (MLAGs) is introduced in chapter 4. An MLAG is a simple, graph-based framework that allows to model most of the theoretical and practical approaches to IR presented in chapter 3. Moreover, it provides an easy-to-grasp way of defining and including new entities into IR modeling, such as paragraphs or peers, dividing them conceptually while at the same time connecting them to each other in a meaningful way. This allows for a unified view on many IR tasks, including that of distributed and peer-to-peer search. Starting from related work and a formal defiition of the framework, the possibilities of modeling that it provides are discussed in detail, followed by an experimental section that shows how new insights gained from modeling inside the framework can lead to novel combinations of principles and eventually to improved retrieval effectiveness.

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 1482) [ClassicSimilarity], result of:
          0.031382043 = score(doc=1482,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.19345059 = fieldWeight in 1482, 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=1482)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date

22. 5.2005 18:25:26

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 2460) [ClassicSimilarity], result of:
          0.031382043 = score(doc=2460,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.19345059 = fieldWeight in 2460, 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=2460)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Abstract

Die ständig steigende Zahl an publizierter Information in immer neuen Formen verlangt besonders von Informations- und Dokumentationseinrichtungen immer präzisere Lösungen zur Erschließung dieser Informationen und ihrer benutzerfreundlichen Aufbereitung. Besonders im derzeitigen Zeitalter der Datenbanken und Online-Kataloge ist die Kombination von verbaler und klassifikatorischer Sacherschließung gefordert, ohne dabei die Verbindung zu den älteren, vielerorts noch (zumindest zusätzlich) in Verwendung befindlichen, Zettelkatalogen zu verlieren. Weltweit ist eine Vielzahl an verschiedenen Klassifikationen im Einsatz. Die Wahl der für eine Einrichtung passenden Klassifikation ist abhängig von ihrer thematischen und informationellen Ausrichtung, der Größe und Art der Bestände und nicht zuletzt von technischen und personellen Voraussetzungen. Auf Seiten der zu wählenden Klassifikation sind die Einfachheit der Handhabung für den Bibliothekar, die Verständlichkeit für den Benutzer, die Erweiterungsfähigkeit der Klassifikation durch das Aufkommen neuer Wissensgebiete und die Einbindung in informationelle Netze mit anderen Einrichtungen von entscheidender Bedeutung. In dieser Arbeit soll die Dewey Dezimalklassifikation (DDC) hinsichtlich dieser Punkte näher beleuchtet werden. Sie ist die weltweit am häufigsten benutzte Klassifikation. Etwa 200.000 Bibliotheken in 135 Ländern erschließen ihre Bestände mit diesem System. Sie liegt derzeit bereits in der 22. ungekürzten Auflage vor und wurde bisher in 30 Sprachen übersetzt. Eine deutsche Komplettübersetzung wird im Jahre 2005 erscheinen. Trotz teils heftig geführter Standardisierungsdebatten und Plänen für die Übernahme von amerikanischen Formalerschließungsregeln herrscht in Bezug auf die Sacherschließung unter deutschen Bibliotheken wenig Einigkeit. Die DDC ist in Deutschland und anderen europäischen Ländern kaum verbreitet, sieht von Großbritannien und von der Verwendung in Bibliografien ab. Diese Arbeit geht demzufolge auf die historischen Gründe dieser Entwicklung ein und wagt einen kurzen Ausblick in die Zukunft der Dezimalklassifikation.

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 4333) [ClassicSimilarity], result of:
          0.031382043 = score(doc=4333,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.19345059 = fieldWeight in 4333, 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=4333)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Pages

22 S

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 867) [ClassicSimilarity], result of:
          0.031382043 = score(doc=867,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.19345059 = fieldWeight in 867, 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=867)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Pages

22 S

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 1670) [ClassicSimilarity], result of:
          0.031382043 = score(doc=1670,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.19345059 = fieldWeight in 1670, 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=1670)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date

26. 9.2006 21:00:22

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 595) [ClassicSimilarity], result of:
          0.031382043 = score(doc=595,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.19345059 = fieldWeight in 595, 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=595)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date

3. 2.2013 18:00:22

0.0039227554 = product of:
  0.015691021 = sum of:
    0.015691021 = product of:
      0.031382043 = sum of:
        0.031382043 = weight(_text_:22 in 642) [ClassicSimilarity], result of:
          0.031382043 = score(doc=642,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = 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)
  0.25 = coord(1/4)

Date

22. 7.2022 12:16:58

0.0032675539 = product of:
  0.0130702155 = sum of:
    0.0130702155 = product of:
      0.026140431 = sum of:
        0.026140431 = weight(_text_:aspects in 4232) [ClassicSimilarity], result of:
          0.026140431 = score(doc=4232,freq=2.0), product of:
            0.20938325 = queryWeight, product of:
              4.5198684 = idf(docFreq=1308, maxDocs=44218)
              0.046325076 = queryNorm
            0.1248449 = fieldWeight in 4232, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              4.5198684 = idf(docFreq=1308, maxDocs=44218)
              0.01953125 = fieldNorm(doc=4232)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Abstract

When we speak about finding relationships between resources, it is necessary to dive deeper in the structure. The graph structure of linked data where the semantics give meaning to the relationships between resources enable the execution of pathfinding algorithms. The assigned weights and heuristics are base components of such algorithms and ultimately define (the order) which resources are included in a path. These paths explain indirect connections between resources. Our third technique proposes an algorithm that optimizes the choice of resources in terms of serendipity. Some optimizations guard the consistence of candidate-paths where the coherence of consecutive connections is maximized to avoid trivial and too arbitrary paths. The implementation uses the A* algorithm, the de-facto reference when it comes to heuristically optimized minimal cost paths. The effectiveness of paths was measured based on common automatic metrics and surveys where the users could indicate their preference for paths, generated each time in a different way. Finally, all our techniques are applied to a use case about publications in digital libraries where they are aligned with information about scientific conferences and researchers. The application to this use case is a practical example because the different aspects of exploratory search come together. In fact, the techniques also evolved from the experiences when implementing the use case. Practical details about the semantic model are explained and the implementation of the search system is clarified module by module. The evaluation positions the result, a prototype of a tool to explore scientific publications, researchers and conferences next to some important alternatives.

0.003138204 = product of:
  0.012552816 = sum of:
    0.012552816 = product of:
      0.025105633 = sum of:
        0.025105633 = weight(_text_:22 in 4399) [ClassicSimilarity], result of:
          0.025105633 = score(doc=4399,freq=2.0), product of:
            0.16222252 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046325076 = queryNorm
            0.15476047 = fieldWeight in 4399, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.03125 = fieldNorm(doc=4399)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date

20. 1.2015 18:30:22