Prof. Dr. Christoph Schmitz

2021 hadoop hdfs fragmentation

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  Schmitz, C., Peled, G., Koren, O.: Small Files in HDFS and Their Impact on Hadoop Performance. Proceedings of the International Conference on Information Integration and Web-Based Applications & Services (IIWAS 2021). 2021 hadoop hdfs fragmentation.

2010

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  Benz, D., Hotho, A., Jäschke, R., Krause, B., Mitzlaff, F., Schmitz, C., Stumme, G.: The social bookmark and publication management system bibsonomy. The VLDB Journal. 19, 849–875 (2010). https://doi.org/10.1007/s00778-010-0208-4.

  Social resource sharing systems are central elements of the Web 2.0 and use the same kind of lightweight knowledge representation, called folksonomy. Their large user communities and ever-growing networks of user-generated content have made them an attractive object of investigation for researchers from different disciplines like Social Network Analysis, Data Mining, Information Retrieval or Knowledge Discovery. In this paper, we summarize and extend our work on different aspects of this branch of Web 2.0 research, demonstrated and evaluated within our own social bookmark and publication sharing system BibSonomy, which is currently among the three most popular systems of its kind. We structure this presentation along the different interaction phases of a user with our system, coupling the relevant research questions of each phase with the corresponding implementation issues. This approach reveals in a systematic fashion important aspects and results of the broad bandwidth of folksonomy research like capturing of emergent semantics, spam detection, ranking algorithms, analogies to search engine log data, personalized tag recommendations and information extraction techniques. We conclude that when integrating a real-life application like BibSonomy into research, certain constraints have to be considered; but in general, the tight interplay between our scientific work and the running system has made BibSonomy a valuable platform for demonstrating and evaluating Web 2.0 research.

2009

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  Hotho, A., Jäschke, R., Benz, D., Grahl, M., Krause, B., Schmitz, C., Stumme, G.: Social Bookmarking am Beispiel BibSonomy. In: Blumauer, A. and Pellegrini, T. (eds.) Social Semantic Web. pp. 363–391. Springer, Berlin, Heidelberg (2009). https://doi.org/10.1007/978-3-540-72216-8.

  BibSonomy ist ein kooperatives Verschlagwortungssystem (Social Bookmarking System), betrieben vom Fachgebiet Wissensverarbeitungder Universit{ä}t Kassel. Es erlaubt das Speichern und Organisieren von Web-Lesezeichen und Metadaten für wissenschaftlichePublikationen. In diesem Beitrag beschreiben wir die von BibSonomy bereitgestellte Funktionalit{ä}t, die dahinter stehende Architektursowie das zugrunde liegende Datenmodell. Ferner erläutern wir Anwendungsbeispiele und gehen auf Methoden zur Analyse der in BibSonomy und ähnlichen Systemen enthaltenen Daten ein.

2008

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  Jäschke, R., Hotho, A., Schmitz, C., Ganter, B., Stumme, G.: Discovering Shared Conceptualizations in Folksonomies. Web Semantics: Science, Services and Agents on the World Wide Web. 6, 38–53 (2008).

  Social bookmarking tools are rapidly emerging on the Web. In such systems users are setting up lightweight conceptual structures called folksonomies. Unlike ontologies, shared conceptualizations are not formalized, but rather implicit. We present a new data mining task, the mining of all frequent tri-concepts, together with an efficient algorithm, for discovering these implicit shared conceptualizations. Our approach extends the data mining task of discovering all closed itemsets to three-dimensional data structures to allow for mining folksonomies. We provide a formal definition of the problem, and present an efficient algorithm for its solution. Finally, we show the applicability of our approach on three large real-world examples.
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  J{ä}schke, R., Hotho, A., Schmitz, C., Ganter, B., Stumme, G.: Discovering Shared Conceptualizations in Folksonomies. Web Semantics. 6, 38–53 (2008). https://doi.org/10.1016/j.websem.2007.11.004.

  Social bookmarking tools are rapidly emerging on the Web. In such systems users are setting up lightweight conceptual structures called folksonomies. Unlike ontologies, shared conceptualizations are not formalized, but rather implicit. We present a new data mining task, the mining of all frequent tri-concepts, together with an efficient algorithm, for discovering these implicit shared conceptualizations. Our approach extends the data mining task of discovering all closed itemsets to three-dimensional data structures to allow for mining folksonomies. We provide a formal definition of the problem, and present an efficient algorithm for its solution. Finally, we show the applicability of our approach on three large real-world examples.
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  Krause, B., Schmitz, C., Hotho, A., Stumme, G.: The Anti-Social Tagger - Detecting Spam in Social Bookmarking Systems. In: Proc. of the Fourth International Workshop on Adversarial Information Retrieval on the Web (2008).

2007

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  Catutto, C., Schmitz, C., Baldassarri, A., Servedio, V.D.P., Loreto, V., Hotho, and A., Grahl, M., Stumme, G.: Network Properties of Folksonomies. AI Communications Journal, Special Issue on "Network Analysis in Natural Sciences and Engineering". (2007).
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  Jäschke, R., Grahl, M., Hotho, A., Krause, B., Schmitz, C., Stumme, G.: Organizing Publications and Bookmarks in BibSonomy. In: Alani, H., Noy, N., Stumme, G., Mika, P., Sure, Y., and Vrandecic, D. (eds.) Workshop on Social and Collaborative Construction of Structured Knowledge (CKC 2007) at WWW 2007. , Banff, Canada (2007).
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  Schmitz, C., Grahl, M., Hotho, A., Stumme, G., Catutto, C., Baldassarri, A., Loreto, V., Servedio, V.D.P.: Network Properties of Folksonomies. In: Proc. WWW2007 Workshop ``Tagging and Metadata for Social Information Organization’’. , Banff (2007).
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  Schmitz, C.: Self-Organized Collaborative Knowledge Management, http://www.uni-kassel.de/upress/online/frei/978-3-89958-325-0.volltext.frei.pdf, (2007).
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  Jäschke, R., Hotho, A., Schmitz, C., Stumme, G.: Analysis of the Publication Sharing Behaviour in {BibSonomy}. In: Proceedings of the 15th International Conference on Conceptual Structures. , Sheffield, England (2007).

  BibSonomy is a web-based social resource sharing system which allows users to organise and share bookmarks and publications in a collaborative manner. In this paper we present the system, followed by a description of the insights in the structure of its bibliographic data that we gained by applying techniques we developed in the area of Formal Concept Analysis.

2006

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  Schmitz, C., Hotho, A., Jäschke, R., Stumme, G.: Content Aggregation on Knowledge Bases using Graph Clustering. In: Proceedings of the 3rd European Semantic Web Conference. , Budva, Montenegro (2006).
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  Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: {BibSonomy}: A Social Bookmark and Publication Sharing System. In: Proceedings of the Conceptual Structures Tool Interoperability Workshop at the 14th International Conference on Conceptual Structures (2006).
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  Schmitz, C., Hotho, A., Jäschke, R., Stumme, G.: Kollaboratives Wissensmanagement. In: Pellegrini, T. and Blumauer, A. (eds.) Semantic Web - Wege zur vernetzten Wissensgesellschaft. pp. 273–290. Springer (2006).

  Wissensmanagement in zentralisierten Wissensbasen erfordert einen hohen Aufwand für Erstellung und Wartung, und es entspricht nicht immer den Anforderungen der Benutzer. Wir geben in diesem Kapitel einen Überblick über zwei aktuelle Ansätze, die durch kollaboratives Wissensmanagement diese Probleme lösen können. Im Peer-to-Peer-Wissensmanagement unterhalten Benutzer dezentrale Wissensbasen, die dann vernetzt werden können, um andere Benutzer eigene Inhalte nutzen zu lassen. Folksonomies versprechen, die Wissensakquisition so einfach wie möglich zu gestalten und so viele Benutzer in den Aufbau und die Pflege einer gemeinsamen Wissensbasis einzubeziehen.
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  Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: FolkRank: A Ranking Algorithm for Folksonomies. In: Proc. FGIR 2006. p. to appear (2006).

  In social bookmark tools users are setting up lightweight conceptual structures called folksonomies. Currently, the information retrieval support is limited. We present a formal model and a new search algorithm for folksonomies, called FolkRank, that exploits the structure of the folksonomy. The proposed algorithm is also applied to find communities within the folksonomy and is used to structure search results. All findings are demonstrated on a large scale dataset. A long version of this paper has been published at the European Semantic Web Conference 2006.
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  Alani, H., Hoser, B., Schmitz, C., Stumme, G. eds.: Proceedings of the 2nd Workshop on Semantic Network Analysis. (2006).
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  Jäschke, R., Hotho, A., Schmitz, C., Stumme, G.: Wege zur Entdeckung von Communities in Folksonomies. In: Braß, S. and Hinneburg, A. (eds.) Proc. 18. Workshop Grundlagen von Datenbanken. pp. 80–84. Martin-Luther-Universität, Halle-Wittenberg (2006).
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  Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: Information Retrieval in Folksonomies: Search and Ranking. In: Proceedings of the 3rd European Semantic Web Conference. , Budva, Montenegro (2006).
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  Hoser, B., Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: Semantic Network Analysis of Ontologies. In: Proceedings of the 3rd European Semantic Web Conference. , Budva, Montenegro (2006).
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  Schmitz, C., Hotho, A., Jäschke, R., Stumme, G.: Mining Association Rules in Folksonomies. In: Proc. IFCS 2006 Conference. , Ljubljana (2006).
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  Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: Emergent Semantics in BibSonomy. In: Proc. Workshop on Applications of Semantic Technologies, Informatik 2006. , Dresden (2006).
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  Schmitz, C., Löser, A.: How to model Semantic Peer-to-Peer Overlays?. In: Proc. P2PIR Workshop, Informatik 2006. , Dresden (2006).
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  Jäschke, R., Hotho, A., Schmitz, C., Ganter, B., Stumme, G.: TRIAS - An Algorithm for Mining Iceberg Tri-Lattices. In: Proc. 6th ICDM conference. , Hong Kong (2006).
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  Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: Trend Detection in Folksonomies. In: Prof. First International Conference on Semantics And Digital Media Technology (SAMT) (to appear). , Athens, Greece (2006).
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  Hotho, A., Jäschke, R., Schmitz, C., Stumme, G.: {BibSonomy}: A Social Bookmark and Publication Sharing System. In: de Moor, A., Polovina, S., and Delugach, H. (eds.) Proceedings of the Conceptual Structures Tool Interoperability Workshop at the 14th International Conference on Conceptual Structures. Aalborg University Press, Aalborg, Denmark (2006).

2005

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  Stumme, G., Hoser, B., Schmitz, C., Alani, H. eds.: ISWC 2005 Workshop on Semantic Network Analysis. , Galway, Ireland (2005).
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  Haase, P., Schmitz, C., Sure, Y. eds.: Ontologies in Peer-to-Peer Communities. , Heraklion, Greece (2005).
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  Schmitz, C.: Towards Self-Organizing Communities in Peer-to-Peer Knowledge Management. In: Proc. ESWC 2005 Workshop on Ontologies in Peer-to-Peer Communities. , Heraklion, Greece (2005).
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  Schmitz, C.: Towards Content Aggregation on Knowledge Bases through Graph Clustering. In: Braß, S. and Goldberg, C. (eds.) Proc. 17. GI-Workshop ``Grundlagen von Datenbanken’’. , Wörlitz (2005).

2004

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  Tane, J., Schmitz, C., Stumme, G.: Semantic Resource Management for the Web: An ELearning Application. In: Proc. 13th International World Wide Web Conference (WWW 2004). , New York (2004).
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  Nejdl, W., Wolpers, M., Siberski, W., Schmitz, C., Schlosser, M., Brunkhorst, I., Löser, A.: Super-Peer-Based Routing Strategies for {RDF}-Based Peer-to-Peer Networks. Journal of Web Semantics. Special issue WWW 2003, (2004).
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  Ehrig, M., Hartmann, J., Schmitz, C.: {O}ntologie-basiertes {W}eb {M}ining. In: Workshop ``Semantische Technologien für Informationsportale’’ (GI-Jahrestagung 2004). Gesellschaft für Informatik (2004).
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  Schmitz, C., Staab, S., Tempich, C.: Socialisation in Peer-to-Peer Knowledge Management. In: Proc. International Conference on Knowledge Management (I-Know 2004). , Graz, Austria (2004).
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  Schmitz, C.: Self-Organization of a Small World by Topic. In: Proc. 1st International Workshop on Peer-to-Peer Knowledge Management. , Boston, MA (2004).

2003

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  Tane, J., Schmitz, C., Stumme, G., Staab, S., Studer, R.: The {C}ourseware {W}atchdog: an ontology-based tool for finding and organizing learning material. In: Fachtagung ``Mobiles Lernen und Forschen’’. , Kassel (2003).
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  Nejdl, W., Wolpers, M., Siberski, W., Schmitz, C., Schlosser, M., Brunkhorst, I., Löser, A.: Super-Peer-Based Routing and Clustering Strategies for {RDF}-Based Peer-To-Peer Networks. In: Proceedings of the 12th International World Wide Web Conference. , Budapest (2003).
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  Ehrig, M., Schmitz, C., Staab, S., Tane, J., Tempich, C.: Towards Evaluation of Peer-to-Peer-based Distributed Information Management Systems. In: Proceedings of the AAAI Spring Symposium on Agent-Mediated Knowledge Management (AMKM-03). , Stanford (2003).
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  Stumme, G., Ehrig, M., Handschuh, S., Hotho, A., Maedche, A., Motik, B., Oberle, D., Schmitz, C., Staab, S., Stojanovic, L., Stojanovic, N., Studer, R., Sure, Y., Volz, R., Zacharias, V.: The {K}arlsruhe view on ontologies. University of Karlsruhe, Institute AIFB (2003).

2002

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  Schmitz, C., Staab, S., Studer, R., Stumme, G., Tane, J.: Accessing Distributed Learning Repositories through a {C}ourseware {W}atchdog. In: Proc. E-Learn 2002: World Conference on E-Learning in Corporate, Government, Healthcare, \& Higher Education. , Montreal (2002).
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  Ehrig, M., Handschuh, S., Hotho, A., Maedche, A., Motik, B., Oberle, D., Schmitz, C., Staab, S., Stojanovic, L., Stojanovic, N., Studer, R., Stumme, G., Sure, Y., Tane, J., Volz, R., Zacharias, V.: {KAON} - Towards a large scale {S}emantic {W}eb. In: Bauknecht, K., Tjoa, A.M., and Quirchmayr, G. (eds.) Proc. E-Commerce and Web Technologies, Third International Conference, EC-Web 2002. Springer, Aix-en-Provence %, France (2002).

2001

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  Schmitz, C.: {U}ntersuchung der {G}raphstruktur von {W}eb-{C}ommunities am {B}eispiel der {I}nformatik, https://www.kde.cs.uni-kassel.de/schmitz/publ/da_schmitz.pdf, (2001).