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<pdf width="1500px">https://ceur-ws.org/Vol-770/foreword.pdf</pdf>
<pre>
Preface
The 2011 ECML-PKDD Discovery Challenge deals with the learning problems
from the domain of recommender systems. Datasets and problems designed by
the organizers of this Challenge, originate from the VideoLectures.Net site, a
free and open access multimedia repository of video lectures, mainly of research
and educational character. The lectures are given by distinguished scholars and
scientists at the most important and prominent events like conferences, summer
schools, workshops and science promotional events from many fields of science.
The Challenge was organized with multiple aims in mind: to improve the cur-
rent websites recommender system, discover new algorithms or computational
workflows and provide new dataset for the research community. It encompassed
two tasks: first one related to new-user/new-item recommendation problem,
and the second task in which ”normal mode”, click-stream based recommen-
dation is simulated. Dataset for the challenge is somewhat specific as it does
not include any explicit nor implicit user preference data. Instead, implicit
profiles embodied in viewing sequences have been transformed into a graph of
lecture co-viewing frequencies and pooled viewing sequences. The data also in-
cludes content related information: topic taxonomy, lecture titles, descriptions
and slide titles, authors’ data, institutions, lecture events and timestamps. The
dataset (including the leaderboard and the test set) will remain publicly avail-
able for experimentation after the end of the challenge.
    Over 300 teams registered for the challenge, resulting in more than 2000
submitted results for the evaluation from 62/22 active teams for task 1 and task
2, respectively. The teams approached the tasks with diverse algorithms and
in several cases novel feature construction approaches. The following are the
winners of the challenge:

Task 1 Cold-start problem:
        • Alexander Dýakonov (1st place)
        • Eleftherios Spyromitros-Xioufis, Emmanouela Stachtiari, Grigorios
          Tsoumakas, and Ioannis Vlahavas (2nd place)
        • Martin Možina, Aleksander Sadikov, and Ivan Bratko (3rd place)
Task 2 Pooled sequence recommendation:
        • Alexander Dýakonov (1st place)
        • Javier Kreiner (2nd place)
        • Vladimir Nikulin (3rd place)

    The Discovery Challenge workshop at the ECML-PKDD 20011 conference
in Athens is aimed for discussion of the results, approaches, VL.net dataset and
lecture recommendation setting in general. We wish to express our gratitude
to:

   • the participants of the challenge,
   • the authors of the submitted papers,
   • Viidea Ltd for disclosing the data on video lectures and for the technical
     support

                                                          Tomislav Šmuc
   Zagreb
                                                    Nino Antulov-Fantulin
   August 2011
                                                           Mikolaj Morzy


   This workshop was supported by the European Union Collaborative Project
e-LICO (e-LICO: An e-Laboratory for Interdisciplinary Collaborative Research
in Data Mining and Data-Intensive Science GA 231519). The partners of e-
LICO are:

   • University of Geneva - Co-ordinator (Switzerland)
   • Institut National de la Sant et de la Recherche Mdicale (France)
   • Jošef Stefan Institute (Slovenia)
   • National Hellenic Research Foundation (Greece)
   • Poznań University of Technology (Poland)
   • Rapid-I GmbH (Germany)
   • Rudjer Bošković Institute (Croatia)
   • University of Manchester (UK)
   • University of Zurich (Switzerland)

</pre>