@inproceedings{1661779,
  abstract = {A folksonomy refers to a collection of user-defined tags with which users describe contents published on the Web. With the flourish of Web 2.0, folksonomies have become an important mean to develop the Semantic Web. Because tags in folksonomies are authored freely, there is a need to understand the structure and semantics of these tags in various applications. In this paper, we propose a learning approach to create an ontology that captures the hierarchical semantic structure of folksonomies. Our experimental results on two different genres of real world data sets show that our method can effectively learn the ontology structure from the folksonomies.},
  address = {San Francisco, CA, USA},
  author = {Tang, Jie and fung Leung, Ho and Luo, Qiong and Chen, Dewei and Gong, Jibin},
  booktitle = {IJCAI'09: Proceedings of the 21st international jont conference on Artifical intelligence},
  interhash = {17f95a6ba585888cf45443926d8b7e98},
  intrahash = {7b335f08a288a79eb70eff89f1ec7630},
  location = {Pasadena, California, USA},
  pages = {2089--2094},
  publisher = {Morgan Kaufmann Publishers Inc.},
  title = {Towards ontology learning from folksonomies},
  url = {http://ijcai.org/papers09/Papers/IJCAI09-344.pdf},
  year = 2009
}

@mastersthesis{stützer2008ol,
  address = {Kassel},
  author = {Stützer, Stefan},
  interhash = {9426b67db29c7270955ae22202c28c82},
  intrahash = {23b133bc2e6a4e00ab243efa98a02a12},
  school = {University of Kassel},
  title = {Lernen von Ontologien aus kollaborativen Tagging-Systemen},
  type = {Master Thesis},
  year = 2009
}

@inproceedings{schmitz06,
  author = {Schmitz, Patrick},
  booktitle = {Collaborative Web Tagging Workshop at WWW2006, Edinburgh, Scotland},
  interhash = {1335f4ef87f951e6edf4fd94f885d3a2},
  intrahash = {77143fd854a06583430afae1371fad71},
  month = May,
  title = {Inducing Ontology from Flickr Tags.},
  url = {http://www.ibiblio.org/www_tagging/2006/22.pdf},
  year = 2006
}

@inproceedings{Van-Damme2007,
  address = {Innsbruck},
  author = {Damme, C{\'e}line Van and Hepp, Martin and Siorpaes, Katharina},
  bdsk-file-1 = {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},
  bdsk-url-1 = {http://www.kde.cs.uni-kassel.de/ws/eswc2007/proc/ProceedingsSemnet07.pdf},
  booktitle = {Bridging the Gap between Semantic Web and Web 2.0 (SemNet 2007)},
  date-added = {2009-08-17 11:40:57 +0200},
  date-modified = {2010-01-04 09:30:08 +0100},
  interhash = {c8d1bcaa606229417f1c3f0f27c5f0e0},
  intrahash = {8d57c1e57c7aba60acb767e3d5b0fa13},
  pages = {57--70},
  title = {FolksOntology: An Integrated Approach for Turning Folksonomies into Ontologies},
  url = {http://www.kde.cs.uni-kassel.de/ws/eswc2007/proc/ProceedingsSemnet07.pdf},
  urldate = {28.5.2008},
  year = 2007
}

@inproceedings{plangprasopchok2009,
  abstract = {Automatic folksonomy construction from tags has attracted much attention recently. However, inferring hierarchical relations between concepts from tags has a drawback in that it is difficult to distinguish between more popular and more general concepts. Instead of tags we propose to use user-specified relations for learning folksonomy. We explore two statistical frameworks for aggregating many shallow individual hierarchies, expressed through the collection/set relations on the social photosharing site Flickr, into a common deeper folksonomy that reflects how a community organizes knowledge. Our approach addresses a number of challenges that arise while aggregating information from diverse users, namely noisy vocabulary, and variations in the granularity level of the concepts expressed. Our second contribution is a method for automatically evaluating learned folksonomy by comparing it to a reference taxonomy, e.g., the Web directory created by the Open Directory Project. Our empirical results suggest that user-specified relations are a good source of evidence for learning folksonomies.},
  address = {New York, NY, USA},
  author = {Plangprasopchok, A. and Lerman, K.},
  booktitle = {WWW '09: Proceedings of the 18th international conference on World wide web},
  doi = {http://doi.acm.org/10.1145/1526709.1526814},
  interhash = {fccd894a82edb040d7438d6da91e3ebe},
  intrahash = {559ee9d48f1a510f56765b2357aa8ea5},
  isbn = {978-1-60558-487-4},
  location = {Madrid, Spain},
  pages = {781--790},
  publisher = {ACM},
  title = {Constructing folksonomies from user-specified relations on flickr},
  url = {http://www2009.org/proceedings/pdf/p781.pdf},
  year = 2009
}

@techreport{citeulike:739394,
  abstract = {Collaborative tagging systems---systems where many casual users annotate objects with free-form strings (tags) of their choosing---have recently emerged as a powerful way to label and organize large collections of data. During our recent investigation into these types of systems, we discovered a simple but remarkably effective algorithm for converting a large corpus of tags annotating objects in a tagging system into a navigable hierarchical taxonomy of tags. We first discuss the algorithm and then present a preliminary model to explain why it is so effective in these types of systems.},
  author = {Heymann, Paul and Garcia-Molina, Hector},
  citeulike-article-id = {739394},
  institution = {Computer Science Department},
  interhash = {d77846b40aadb0e25233cabf905bb93e},
  intrahash = {3b4ce6fd7fa6dbf1c39fd261fa39fcd6},
  month = {April},
  number = {2006-10},
  priority = {3},
  school = {Standford University},
  title = {Collaborative Creation of Communal Hierarchical Taxonomies in Social Tagging Systems},
  url = {http://dbpubs.stanford.edu:8090/pub/2006-10},
  year = 2006
}

@inproceedings{Zhou/2007/Unsupervised,
  abstract = {This paper deals with the problem of exploring hierarchical semantics from social annotations. Recently, social annotation services have become more and more popular in Semantic Web. It allows users to arbitrarily annotate web resources, thus, largely lowers the barrier to cooperation. Furthermore, through providing abundant meta-data resources, social annotation might become a key to the development of Semantic Web. However, on the other hand, social annotation has its own apparent limitations, for instance, 1) ambiguity and synonym phenomena and 2) lack of hierarchical information. In this paper, we propose an unsupervised model to automatically derive hierarchical semantics from social annotations. Using a social bookmark service Del.icio.us as example, we demonstrate that the derived hierarchical semantics has the ability to compensate those shortcomings. We further apply our model on another data set from Flickr to testify our model's applicability on different environments. The experimental results demonstrate our model's effciency.},
  address = {Berlin, Heidelberg},
  author = {Zhou, Mianwei and Bao, Shenghua and Wu, Xian and Yu, Yong},
  booktitle = {Proceedings of the 6th International Semantic Web Conference and 2nd Asian Semantic Web Conference (ISWC/ASWC2007), Busan, South Korea},
  crossref = {http://data.semanticweb.org/conference/iswc-aswc/2007/proceedings},
  editor = {Aberer, Karl and Choi, Key-Sun and Noy, Natasha and Allemang, Dean and Lee, Kyung-Il and Nixon, Lyndon J B and Golbeck, Jennifer and Mika, Peter and Maynard, Diana and Schreiber, Guus and Cudré-Mauroux, Philippe},
  interhash = {af21595ee9f4a13b5e651ad049f31262},
  intrahash = {355fcbb32255f3ba5f41819c00c520ba},
  month = {November},
  pages = {673--686},
  publisher = {Springer Verlag},
  series = {LNCS},
  title = {An Unsupervised Model for Exploring Hierarchical Semantics from Social Annotations},
  url = {http://iswc2007.semanticweb.org/papers/673.pdf},
  volume = 4825,
  year = 2007
}