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We have developed a file and bookmark sharing system, called Comtella. The system allows CS researchers and students to share papers (either their own, or downloaded from the web) and to search for papers among those that are shared by them or their colleagues. In this way, by sharing papers, people contribute to creating a shared and distributed digital library with zero maintenance costs.


Comtella does not aim to replace web-based search engines like Google, CiteSeer or various Bibtex bibliographies. Its purpose is to manage the files that you find using those engines and bibliographies and decide to save for future use. Generally, people either print or save local copies of good papers they find online, since bookmarking often leads to disappointment, e.g. hanging links, changes in access permissions to websites etc. However, as the number of printed or saved copies increases, it becomes increasingly difficult to find that interesting paper you are sure you must have somewhere in your files. Comtella can help you find this paper on your own disk. Moreover, it will help you find papers that other colleagues using Comtella have considered useful and saved on their hard disks. The price for this convenience is that you need to annotate the paper when you save it (you will be prompted by Comtella to save and share each .pdf or .ps file that you are viewing long enough in your browser) according to a category - subcategory index (we use the ACM subject category index). This annotation will be used later to search for the paper. For this, you have to select the category and subcategory of the paper and Comtella will give you a list of all papers that you have stored in this category as well as those that your peers who are currently on-line have stored. We see the biggest value for research groups, where graduate and honours students, professors, summer students, doing research in particular area can benefit from putting together their search efforts to share papers in their areas of interest seamlessly. You won't need to e-mail a paper that you think will be interesting to a colleague, since s/he will be able to find the paper from your files with Comtella. Your colleagues and you most likely have closely matching interests, so papers saved by them will likely be of value for you too.

RESEARCH QUESTION: How to Encourage Participation in Online Communities, and in the Participative Web (Web 2.0)

Stimulating users to participate is the main problem in this systems, since there have been so many unsuccessful systems, though designed well, tested for usability according to good HCI principles etc. In our research , we have explored different ways of incorporating incentives (rewards) for desirable participatory actions. People are economical beings and respond to incentives. However, the incentives that work for different people are different. Some are motivated by money, others - by glory, some - by power, others - by building relationships with people, and yet others are altruists finding rewards in working for a good cause or in heaven. We have found that through incorporating appropriate incentives - for example, rewarding users with higher status, we can increase participation in an online community. By appropriate adaptation of the rewards, one can stimulate the desired type of participation in a desired time. Through introducing virtual currency that can be used by users to bring up their own papers in the list of search results (like Google's sponsored links), we were able to double the number of ratings that users gave in the system. We have explored also the use of a social visualization to stimulate social comparison and competition to stimulate users motivated by glory and social status to participate and to stimulate people who are interested in developing symmetricalinterpersonal relationships.

This topic is very interdisciplinary - it is on the cross-roads of HCI, visualization, game design, economics, social psychology and AI. I am looking for a student who is both excellent in CS, but also has artistic talent and original creative nature. From reading your application, I think that you may be this student.


Entangling Lurkers in a Net of Relationships

Semantic Social Tagging of Documents



Comtella was demonstrated at the AIED'2005 conference in Amsterdam in an interactive event. Fourteen participants played with the system for about one hour, shared links to papers, pictures, other social software systems and rated the links shared by the other participants.. In the end those who obtained gold memberships received small gifts. The top prize (a framed certificate of achievement) was awarded to Kaspar de Geus, a first year Computer Science student from the University of Amsterdam. In about 45 minutes, he shared 5 papers, which obtained 7 ratings from others, he also rated 23 links shared by others.

out A version of Comtella was used in the MADMUC lab to share research papers in among professors and graduate students (June 2005)

Web-based version from Winter 2005 (used in CMPT 408 - Ethics and IT). You can no longer log-in with "comtellaguest" (as both username and password).

See the version used in CMPT 490 (Ethics and IT) Jan-March 2004 (NOT ACTIVE ANYMORE)

DOWNLOAD the latest P2P client (June 21, 2004) for Windows (NOT ACTIVE ANYMORE)



Dr. Julita Vassileva, Associate Professor

Madmuc Lab, Computer Science Department
178 Thorvaldson Bldg, 110 Science Place
University of Saskatchewan, Saskatoon, S7N 5C9

email: jiv AT cs DOT usask DOT ca
phone: (306) 966 2073 or