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.

@article{jaeschke2008discovering, author = {Jäschke, Robert and Hotho, Andreas and Schmitz, Christoph and Ganter, Bernhard and Stumme, Gerd}, title = {Discovering Shared Conceptualizations in Folksonomies}, editor = {Finin, T. and Mizoguchi, R. and Staab, S.}, booktitle = {Semantic Web and Web 2.0}, journal = {Web Semantics: Science, Services and Agents on the World Wide Web}, publisher = {Elsevier}, address = {New York}, year = {2008}, volume = {6}, number = {1}, pages = {38--53}, url = {http://www.sciencedirect.com/science/article/B758F-4R53WD4-1/2/ae56bd6e7132074272ca2035be13781b}, doi = {10.1016/j.websem.2007.11.004}, issn = {1570-8268}, keywords = {2008, analysis, concept, folksonomy, formal, l3s, ol_web2.0, tagging, trias, wp5, methods_concepts, emergentsemantics_evidence}, abstract = {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.} }

%0 = article %A = Jäschke, Robert and Hotho, Andreas and Schmitz, Christoph and Ganter, Bernhard and Stumme, Gerd %B = Semantic Web and Web 2.0 %C = New York %D = 2008 %I = Elsevier %T = Discovering Shared Conceptualizations in Folksonomies %U = http://www.sciencedirect.com/science/article/B758F-4R53WD4-1/2/ae56bd6e7132074272ca2035be13781b

@article{cattuto2007networkb, author = {Cattuto, Ciro and Schmitz, Christoph and Baldassarri, Andrea and Servedio, Vito D. P. and Loreto, Vittorio and Hotho, Andreas and Grahl, Miranda and Stumme, Gerd}, title = {Network Properties of Folksonomies}, editor = {Hoche, Susanne and Nürnberger, Andreas and Flach, Jürgen}, journal = {AI Communications Journal, Special Issue on ``Network Analysis in Natural Sciences and Engineering''}, publisher = {IOS Press}, year = {2007}, volume = {20}, number = {4}, pages = {245-262}, url = {http://www.kde.cs.uni-kassel.de/stumme/papers/2007/cattuto2007network.pdf}, issn = {0921-7126}, keywords = {2007, semantics, emergent, folksonomy, tagorapub, folksonomies, l3s, network, itegpub, fca} }

%0 = article %A = Cattuto, Ciro and Schmitz, Christoph and Baldassarri, Andrea and Servedio, Vito D. P. and Loreto, Vittorio and Hotho, Andreas and Grahl, Miranda and Stumme, Gerd %D = 2007 %I = IOS Press %T = Network Properties of Folksonomies %U = http://www.kde.cs.uni-kassel.de/stumme/papers/2007/cattuto2007network.pdf

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.

@inproceedings{jaeschke2007analysis, author = {Jäschke, Robert and Hotho, Andreas and Schmitz, Christoph and Stumme, Gerd}, title = {Analysis of the Publication Sharing Behaviour in BibSonomy}, editor = {Priss, U. and Polovina, S. and Hill, R.}, booktitle = {Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007)}, series = {Lecture Notes in Artificial Intelligence}, publisher = {Springer-Verlag}, address = {Berlin, Heidelberg}, year = {2007}, volume = {4604}, pages = {283--295}, isbn = {3-540-73680-8}, keywords = {2007, analysis, bibsonomy, bookmarking, fca, folksonomy, iccs, l3s, ol_web2.0, social, trias, widely_related, emergentsemantics_evidence}, abstract = {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.} }

%0 = inproceedings %A = Jäschke, Robert and Hotho, Andreas and Schmitz, Christoph and Stumme, Gerd %B = Proceedings of the 15th International Conference on Conceptual Structures (ICCS 2007) %C = Berlin, Heidelberg %D = 2007 %I = Springer-Verlag %T = Analysis of the Publication Sharing Behaviour in BibSonomy

@inproceedings{jaeschke2007organizing, author = {Jäschke, Robert and Grahl, Miranda and Hotho, Andreas and Krause, Beate and Schmitz, Christoph and Stumme, Gerd}, title = {Organizing Publications and Bookmarks in BibSonomy}, editor = {Alani, Harith and Noy, Natasha and Stumme, Gerd and Mika, Peter and Sure, York and Vrandecic, Denny}, booktitle = {Workshop on Social and Collaborative Construction of Structured Knowledge (CKC 2007) at WWW 2007}, address = {Banff, Canada}, year = {2007}, url = {http://www2007.org/workshops/paper_25.pdf}, keywords = {challenge, 2007, organizing, BibSonomy, bibsonomy, tagorapub, l3s, itegpub} }

%0 = inproceedings %A = Jäschke, Robert and Grahl, Miranda and Hotho, Andreas and Krause, Beate and Schmitz, Christoph and Stumme, Gerd %B = Workshop on Social and Collaborative Construction of Structured Knowledge (CKC 2007) at WWW 2007 %C = Banff, Canada %D = 2007 %T = Organizing Publications and Bookmarks in BibSonomy %U = http://www2007.org/workshops/paper_25.pdf

Social bookmark tools are rapidly emerging on the Web. In suchsystems users are setting up lightweight conceptual structurescalled folksonomies. The reason for their immediate success is thefact that no specific skills are needed for participating. In thispaper we specify a formal model for folksonomies and briefly describe our own system BibSonomy, which allows for sharing both bookmarksand publication references in a kind of personal library.

@inproceedings{hotho2006bibsonomy, author = {Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd}, title = {BibSonomy: A Social Bookmark and Publication Sharing System}, editor = {de Moor, Aldo and Polovina, Simon and Delugach, Harry}, booktitle = {Proceedings of the First Conceptual Structures Tool Interoperability Workshop at the 14th International Conference on Conceptual Structures}, publisher = {Aalborg Universitetsforlag}, address = {Aalborg}, year = {2006}, pages = {87-102}, url = {http://www.kde.cs.uni-kassel.de/stumme/papers/2006/hotho2006bibsonomy.pdf}, isbn = {87-7307-769-0}, keywords = {2006, bookmarking, social, nepomuk, bibsonomy, OntologyHandbook, FCA, folksonomy, tagorapub, iccs, l3s}, abstract = {Social bookmark tools are rapidly emerging on the Web. In suchsystems users are setting up lightweight conceptual structurescalled folksonomies. The reason for their immediate success is thefact that no specific skills are needed for participating. In thispaper we specify a formal model for folksonomies and briefly describe our own system BibSonomy, which allows for sharing both bookmarksand publication references in a kind of personal library.} }

%0 = inproceedings %A = Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd %B = Proceedings of the First Conceptual Structures Tool Interoperability Workshop at the 14th International Conference on Conceptual Structures %C = Aalborg %D = 2006 %I = Aalborg Universitetsforlag %T = BibSonomy: A Social Bookmark and Publication Sharing System %U = http://www.kde.cs.uni-kassel.de/stumme/papers/2006/hotho2006bibsonomy.pdf

Social bookmark tools are rapidly emerging on the Web. In suchsystems users are setting up lightweight conceptual structurescalled folksonomies. The reason for their immediate success is thefact that no specific skills are needed for participating. In thispaper we specify a formal model for folksonomies, briefly describeour own system BibSonomy, which allows for sharing both bookmarks andpublication references, and discuss first steps towards emergent semantics.

@inproceedings{hotho2006emergent, author = {Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd}, title = {Emergent Semantics in BibSonomy}, editor = {Hochberger, Christian and Liskowsky, Rüdiger}, booktitle = {Informatik 2006 -- Informatik für Menschen. Band 2}, series = {Lecture Notes in Informatics}, publisher = {Gesellschaft für Informatik}, address = {Bonn}, year = {2006}, volume = {P-94}, note = {Proc. Workshop on Applications of Semantic Technologies, Informatik 2006}, url = {http://www.kde.cs.uni-kassel.de/stumme/papers/2006/hotho2006emergent.pdf}, keywords = {2006, UniK, bibsonomy, emergence, emergent, folksonomy, hotho, itegpub, jaeschke, l3s, nepomuk, schmitz, semantics, stumme, tagorapub, ol_web2.0, emergentsemantics_evidence}, abstract = {Social bookmark tools are rapidly emerging on the Web. In suchsystems users are setting up lightweight conceptual structurescalled folksonomies. The reason for their immediate success is thefact that no specific skills are needed for participating. In thispaper we specify a formal model for folksonomies, briefly describeour own system BibSonomy, which allows for sharing both bookmarks andpublication references, and discuss first steps towards emergent semantics.} }

%0 = inproceedings %A = Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd %B = Informatik 2006 -- Informatik für Menschen. Band 2 %C = Bonn %D = 2006 %I = Gesellschaft für Informatik %T = Emergent Semantics in BibSonomy %U = http://www.kde.cs.uni-kassel.de/stumme/papers/2006/hotho2006emergent.pdf

Social bookmark tools are rapidly emerging on the Web. In such systems users are setting up lightweight conceptual structures called folksonomies. The reason for their immediate success is the fact that no specific skills are needed for participating. At the moment, however, 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 findcommunities within the folksonomy and is used to structure search results. All findings are demonstrated on a large scale dataset.

@inproceedings{hotho2006information, author = {Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd}, title = {Information Retrieval in Folksonomies: Search and Ranking}, editor = {Sure, York and Domingue, John}, booktitle = {The Semantic Web: Research and Applications}, series = {Lecture Notes in Computer Science}, publisher = {Springer}, address = {Heidelberg}, year = {2006}, volume = {4011}, pages = {411-426}, keywords = {2006, folkrank, folksonomy, graph, iccs_example, information, l3s, mining, ol_web2.0, pagerank, rank, ranking, retrieval, search, seminar2006, testttag, trias_example, webzu, widely_related}, abstract = {Social bookmark tools are rapidly emerging on the Web. In such systems users are setting up lightweight conceptual structures called folksonomies. The reason for their immediate success is the fact that no specific skills are needed for participating. At the moment, however, 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 findcommunities within the folksonomy and is used to structure search results. All findings are demonstrated on a large scale dataset.} }

%0 = inproceedings %A = Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd %B = The Semantic Web: Research and Applications %C = Heidelberg %D = 2006 %I = Springer %T = Information Retrieval in Folksonomies: Search and Ranking

As the number of resources on the web exceeds by far the number ofdocuments one can track, it becomes increasingly difficult to remainup to date on ones own areas of interest. The problem becomes moresevere with the increasing fraction of multimedia data, from whichit is difficult to extract some conceptual description of theircontents.One way to overcome this problem are social bookmark tools, whichare rapidly emerging on the web. In such systems, users are settingup lightweight conceptual structures called folksonomies, andovercome thus the knowledge acquisition bottleneck. As more and morepeople participate in the effort, the use of a common vocabularybecomes more and more stable. We present an approach for discoveringtopic-specific trends within folksonomies. It is based on adifferential adaptation of the PageRank algorithm to the triadichypergraph structure of a folksonomy. The approach allows for anykind of data, as it does not rely on the internal structure of thedocuments. In particular, this allows to consider different datatypes in the same analysis step. We run experiments on a large-scalereal-world snapshot of a social bookmarking system.

@inproceedings{hotho2006trend, author = {Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd}, title = {Trend Detection in Folksonomies}, editor = {Avrithis, Yannis S. and Kompatsiaris, Yiannis and Staab, Steffen and O'Connor, Noel E.}, booktitle = {Proc. First International Conference on Semantics And Digital Media Technology (SAMT) }, series = {LNCS}, publisher = {Springer}, address = {Heidelberg}, year = {2006}, volume = {4306}, pages = {56-70}, url = {http://www.kde.cs.uni-kassel.de/stumme/papers/2006/hotho2006trend.pdf}, isbn = {3-540-49335-2}, keywords = {intranet, 2006, trend, pagerank, hotho, schmitz, jaeschke, l3s, itegpub, detection, triadic, stumme, nepomuk, folksonomy, tagorapub, folkrank, UniK}, abstract = {As the number of resources on the web exceeds by far the number ofdocuments one can track, it becomes increasingly difficult to remainup to date on ones own areas of interest. The problem becomes moresevere with the increasing fraction of multimedia data, from whichit is difficult to extract some conceptual description of theircontents.One way to overcome this problem are social bookmark tools, whichare rapidly emerging on the web. In such systems, users are settingup lightweight conceptual structures called folksonomies, andovercome thus the knowledge acquisition bottleneck. As more and morepeople participate in the effort, the use of a common vocabularybecomes more and more stable. We present an approach for discoveringtopic-specific trends within folksonomies. It is based on adifferential adaptation of the PageRank algorithm to the triadichypergraph structure of a folksonomy. The approach allows for anykind of data, as it does not rely on the internal structure of thedocuments. In particular, this allows to consider different datatypes in the same analysis step. We run experiments on a large-scalereal-world snapshot of a social bookmarking system.} }

%0 = inproceedings %A = Hotho, Andreas and Jäschke, Robert and Schmitz, Christoph and Stumme, Gerd %B = Proc. First International Conference on Semantics And Digital Media Technology (SAMT) %C = Heidelberg %D = 2006 %I = Springer %T = Trend Detection in Folksonomies %U = http://www.kde.cs.uni-kassel.de/stumme/papers/2006/hotho2006trend.pdf

In this paper, we present the foundations for mining frequent tri-concepts, which extend the notion of closed itemsets to three-dimensional data to allow for mining folksonomies. We provide a formal definition of the problem, and present an efficient algorithm for its solution as well as experimental results on a large real-world example.

@inproceedings{jaeschke2006trias, author = {Jäschke, Robert and Hotho, Andreas and Schmitz, Christoph and Ganter, Bernhard and Stumme, Gerd}, title = {TRIAS - An Algorithm for Mining Iceberg Tri-Lattices}, booktitle = {Proceedings of the 6th IEEE International Conference on Data Mining (ICDM 06)}, publisher = {IEEE Computer Society}, address = {Hong Kong}, year = {2006}, pages = {907-911}, url = {http://www.kde.cs.uni-kassel.de/jaeschke/paper/jaeschke06trias.pdf}, doi = {http://doi.ieeecomputersociety.org/10.1109/ICDM.2006.162}, isbn = {0-7695-2701-9}, keywords = {12, 2006, algorithm, fca, iccs_example, l3s, ol_web2.0, trias, trias_example, methods_concepts}, abstract = {In this paper, we present the foundations for mining frequent tri-concepts, which extend the notion of closed itemsets to three-dimensional data to allow for mining folksonomies. We provide a formal definition of the problem, and present an efficient algorithm for its solution as well as experimental results on a large real-world example.} }

%0 = inproceedings %A = Jäschke, Robert and Hotho, Andreas and Schmitz, Christoph and Ganter, Bernhard and Stumme, Gerd %B = Proceedings of the 6th IEEE International Conference on Data Mining (ICDM 06) %C = Hong Kong %D = 2006 %I = IEEE Computer Society %T = TRIAS - An Algorithm for Mining Iceberg Tri-Lattices %U = http://www.kde.cs.uni-kassel.de/jaeschke/paper/jaeschke06trias.pdf