Social Choice Theory (lect. + exerc.)

When groups make collective decisions, choices are supposed to reflect their members preferences: think about a democratic society electing a president or a group of friends ranking potential holiday destinations. This course is dedicated to a mathematically rigorous analysis of how groups can (or cannot) make such collective decisions (i.e. social choices). The first part of the course covers voting theory, the systematic study of election mechanisms that determine a winner based on voters' rankings of alternatives (such as presidential candidates). In the second part of the course, voting theory is embedded into the more general study of abstract aggregation theory which includes the aggregation of preferences or judgments. Along the way, we will prove famous theorems like Arrow's Impossibility Theorem, Gibbard's Oligarchy Theorem or the Gibbard-Satterthwaite Theorem.