Sven Seuken University of Zurich   Department of Informatics University of Zurich Binzmühlestrasse 14 Zürich, ZH 8050 Switzerland   seuken@ifi.uzh.ch   http://www.ifi.uzh.ch/ce/people/seuken.html           JEL Areas: D4 : Market Structure and Pricing: General D8 : Information, Knowledge, and Uncertainty: General