The paper considers a voting model where each voter's type is her preference. The type graph for a voter is a graph whose vertices are the possible types of the voter. Two vertices are connected by an edge in the graph if the associated types are "neighbors." A social choice function is locally...

In a voting model where the set of feasible alternatives is a subset of a product set $A = A_1\times\cdots\ldots{}A_m$ of $m$ finite categories, we characterize the set of all strategy-proof social choice functions for three different types of preference domains over $A$, namely for the domains...

When making collektive desicions, principals (voters or districts) typically benefit by strategically delegating their bargaining and voting power to representatives different from themselves. There are conflicting views in the literature, however, of whether such a delegate should be...

The burgeoning literature on the use of sanctions to support public goods provision has largely neglected the use of formal or centralized sanctions. We let subjects playing a linear public goods game vote on the parameters of a formal sanction scheme capable both of resolving and of...

Five German leading parties and their coalitions are evaluated from the viewpoint of direct democracy. For this purpose, the positions of the parties on over 30 topical issues are compared with the results of polls of public opinion. The outcomes are summarized in the indices of popularity and...

A collective decision problem is described by a set of agents, a profile of single-peaked preferences over the real line and a number k of public facilities to be located. We consider public facilities that do not suffer from congestion and are non-excludable. We provide a characterization of...

Interest groups are introduced in a spatial model of electoral competition between two political parties. We show that, by coordinating voting behavior, these interest groups increase the winning set, which is defined as the set of policy platforms for the challenger that will defeat the...

We set up a model of elections or referendums with two alternatives to study how voter turnout and election outcomes are affected by the publication of exit polls on election day. We find that the introduction of an exit poll influences the incentive to vote both before and after the poll is...

We analyze the voting behavior of a board of directors that has to approve (or reject) an investment proposal with uncertain return. We consider three types of directors: insiders, who are biased toward acceptance of the project, independent outsiders who want to maximize the firm's profit and...

In economics and other social sciences, complex processes are often represented by numerical models of reality which more or less well reflect behavioral relationships and interactions. Such attempts are the subject of a lecture course "Mathematical Theory of Democracy" by the author at the...