Harrie de Swart is a Dutch logician and mathematician with a great and open int- est in applications of logic. After being confronted with Arrows Theorem, Harrie became very interested in social choice theory. In 1986 he took the initiative to start up a group of Dutch scientists for the study of social choice theory. This initiative grew out to a research group and a series of colloquia, which were held approximately every month at the University of Tilburg in The Netherlands. The organization of the colloquia was in the hands of Harrie and under his guidance they became more and more internationally known. Many international scholars liked visiting the social choice colloquia in Tilburg and enjoyed giving one or more presentations about their work. They liked Harries kindness and hospitality, and the openness of the group for anything and everything in the eld of social choice. The Social Choice Theory Group started up by Harrie consisted, and still c- sists, of scholars from several disciplines; mostly economics, mathematics, and (mathematical) psychology. It was set up for the study of and discussion about anything that had to do with social choice theory including, and not in the least, the supervision of PhD students in the theory. Members of the group were, among o- ers, Thom Bezembinder (psychologist), Hans Peters (mathematician), Pieter Ruys (economist), Stef Tijs (mathematician and game theorist) and, of course, Harrie de Swart (logician and mathematician).

From Blacks Advice and Arrows Theorem to the GibbardSatterthewaite Result.- The Impact of Forcing Preference Rankings When Indifference Exists.- Connections and Implications of the Ostrogorski Paradox for Spatial Voting Models.- Maximal Domains for Maskin Monotone Pareto Optimal and Anonymous Choice Rules.- Extremal Restriction, Condorcet Sets, and Majority Decision Making.- Rights Revisited, and Limited.- Some General Results on Responsibility for Outcomes.- Existence of a Dictatorial Subgroup in Social Choice with Independent Subgroup Utility Scales, an Alternative Proof.- Making (Non-standard) Choices.- Puzzles and Paradoxes Involving Averages: An Intuitive Approach.- Voting Weights, Thresholds and Population Size: Member State Representation in the Council of the European Union.- Stabilizing Power Sharing.- Different Approaches to Influence Based on Social Networks and Simple Games.- Networks, Information and Choice.- Characterizations of Bargaining Solutions by Properties of Their Status Quo Sets.- Monotonicity Properties of Interval Solutions and the DuttaRay Solution for Convex Interval Games.