Zoran Despotovic

[PHOTO]Assistent - Doctorant
Distributed Information Systems Laboratory (LSIR)
     - headed by prof. Karl Aberer
School of Computer and Communication Sciences  (I&C)
Swiss Federal Institute of Technology (EPFL)

EPFL IC IIF LSIR
Bâtiment BC, Station 14
CH-1015 Lausanne, Switzerland
Phone: +41 21 693 5260
Fax: +41 21 693 8115
Email: zoran.despotovic@epfl.ch

 Research  Interests| Related Links
 Courses
 Publications
 Professional Activities
 Personal Interests
 Bio

Research Interests and Projects

My primary research interest relates to enabling e-commerce in P2P networks. It mainly deals with designing P2P reputation systems, on the one hand, and P2P-suitable exchange and trading mechanisms, on the other.

bulletP2P Reputation Systems Design

Enabling any kind of commerce has as the very first precondition providing appropriate assurance mechanisms that reduce or eliminate opportunistic behavior of the involved parties. Traditional forms of such mechanisms, such as contractual agreements monitored by enforcement institutions, are not always viable in online world. The main reason is that they become totally inefficient when it comes to crossing jurisdictional borders and when the stakes of the involved transactions are small. Under such circumstances, reputation systems as informal social mechanisms for encouraging trustworthy behavior appear to be the only remaining alternative. Their key presumption is that the participants of an online community are engaged in repeated interactions and that collecting, processing, and disseminating information about their past doings is informative of their future behavior and as such will influence it.

The need for reputation mechanisms is particularly strong in P2P systems as potential marketplaces because the participants' personal feelings of autonomy are amplified by the inherent technological decentralization of the environment. However, the decentralization makes the problem of designing reputation mechanisms substantially harder in P2P networks than in centralized settings. There are at least two reasons for this statement: 1) the reputation data retrieval aspect of problem plays an important role in P2P networks and only a small fraction of the entire available feedback can be used and 2) there is no central trusted authority to aggregate feedback in a particular way to enable the decision making process easy or intuitive.

Our findings on the above issues from a short-term project jointly done with professor Jean-Claude Usunier from University of Lausanne can be found here. The follow-up project, joint with the Artificial Intelligence Laboratory of EPFL and Institute of International Management of University of Lausanne, is currently underway.

bulletDesigning P2P-suitable Exchange and Trading Mechanisms

Once the issue of trust is properly addressed one can think of designing marketplaces on top of P2P platforms. This task implies devising appropriate trading mechanisms but also providing infrastructure for handling payments and exchanges of the traded goods.

In a recent paper I analyzed the existing double auctioning mechanisms in the context of their implementation in P2P networks and proposed a new  mechanism that does not rely on the existence of central authorities, auctioneer in particular. As such it is amenable to implementation in P2P environments. The mechanism is a variation of the continuous double auction slightly adapted to fit the decentralized networked environments. It has good economic properties such as, for example, fast convergence towards efficient trading through intuitive and simple bidding strategies.

If the digital goods are traded then it becomes possible to split both the goods to be delivered and the payments into a number of chunks and organize the deliveries of the chunks in such a way that the risks of the involved partners are minimized. If a reputation mechanism tuned to give probabilities of likely behavior of the parties is underlying the exchange then it is also possible to include this aspect of trust into the delivery schedule. This was the problem I also addressed.

My further research interests include more technological aspects of e-commerce such as business process specifications and langages based on XML and accompanying technologies. More specifically, I worked on the problem of creating process-aware user interface based on XSLT processing. The main contribution of this effort was an architecture with a full realization of the separation of concern principle in which the process specification and the target UI were defined separately but seemingly integrated in runtime .

Related Links

Courses

bulletSummer Semester 2004:
Conception of Information Systems
bulletSummer Semester 2003:
Conception of Information Systems
bulletWinter Semester 2002/2003:
Distributed Information Processing
bulletSummer Semester 2002:
Conception of Information Systems (no longer available online)
bulletWinter Semester 2002/2003:
Distributed Information Systems (no longer available online)
bulletSummer Semester 2002:
Conception of Information Systems (no longer available online)

bullet Publications

     bullet Tutorials
     bullet Technical reports and full versions of the papers

bullet Professional Activities

bullet Personal Interests

Sport
...is definitevely my passion number one. Basketball, footbal, ... , the list is long. Here are some photos: Indianapolis, Bari.
bulletComics
Corto Maltese, of course. Take a look: Corto, Rasputin.
bulletMusic
Clash, Darko Rundek.
bulletFilm
Taxi Driver, Godfather.

bullet Short Bio

I graduated from Faculty of Electrical Engineering (Computer Science Direction) of  University of Belgrade, Serbia and Montenegro in 1995.
I am currently Ph.D. student and teaching assistant at Distributed Information Systems Lab at EPFL, Computer Sience and Communication Systems department. I previously completed the pre-doctoral program at the same department (1999-2000), working on a project related to emerging public key cryptographic schemes. Before moving to Switzerland I worked for three years for Yugoslav Chamber of Commerce and Industry. The main focus of my work there was Web development under at that time emerging Java and XML technologies. I had several publications, mostly on Java, and gave numeruous courses on this programming language.
I am a citizen of Serbia and Montenegro.