Jean-François Laslier

Distributive Politics and Electoral Competition

Abstract Within the framework of pure redistribution (dividing one unit of a homo- geneous good among identical individuals), the paper analyses the redistribution that arises from Downsian, two-party, electoral competition. It appears that the strategic behavior of vote-maximizing parties leads them to propose divisions which are not far from the egalitarian one. Journal of Economic Literature Classification Numbers: C72, D63, D72.

A Behavioral Learning Process in Games

The paper studies a behavioral learning process where an agent plays, at each period, an action with a probability which is proportional to the cumulative utility he got in the past with that action. The so-called CPR learning rule and the dynamic process it induces are formally stated and compared to other reinforcement rules as well as to fictitious play or the replicator dynamics.

Handbook on approval voting

to the Handbook on Approval Voting.- History of Approval Voting.- Acclamation Voting in Sparta: An Early Use of Approval Voting.- Going from Theory to Practice: The Mixed Success of Approval Voting.- Axiomatic Theory.- Collective Choice for Simple Preferences.- Axiomatizations of Approval Voting.- Committees.- Approval Balloting for Multi-winner Elections.- Does Choosing Committees from Approval Balloting Fulfill the Electorates Will?.- Strategic Voting.- The Basic Approval Voting Game.- Approval Voting in Large Electorates.- Computational Aspects of Approval Voting.- Probabilistic Exercises.- On the Condorcet Efficiency of Approval Voting and Extended Scoring Rules for Three Alternatives.- Behavioral Heterogeneity Under Approval and Plurality Voting.- In Silico Voting Experiments.- Experiments.- Laboratory Experiments on Approval Voting.- Framed Field Experiments on Approval Voting: Lessons from the 2002 and 2007 French Presidential Elections.- Approval Voting in Germany: Description of a Field Experiment.- Electoral Competition.- Classical Electoral Competition Under Approval Voting.- Policy Moderation and Endogenous Candidacy in Approval Voting Elections.- Meaning for Individual and Society.- Describing Society Through Approval Data.- Approval as an Intrinsic Part of Preference.

Strategic, Sincere and Heuristic Voting under Four Election Rules: An Experimental Study

We report on laboratory experiments on voting. In a setting where subjects have single-peaked preferences, we find that the rational choice theory provides very good predictions of actual individual behavior in one-round and approval voting elections but fares poorly in explaining vote choice under two-round elections. We conclude that voters behave strategically as far as strategic computations are not too demanding, in which case they rely on simple heuristics (under two-round voting) or they just vote sincerely (under single transferable vote).

Composition-consistent tournament solutions and social choice functions

This paper introduces a new axiom for choice in preference profiles and tournaments, called composition-consistency. A social choice function is composition-consistent if it is non-sensitive to the cloning of one or several outcomes. The key feature of the composition consistency property is an operation concept called multiple composition product of profiles. The paper provides a brief overview of some social choice functions studied in the literature. Concerning the tournament solutions, it is proved that the Top Cycle, the Slater and the Copeland solutions are not composition-consistent, whereas the Banks, Uncovered Set, TEQ, Minimal Covering Set are composition-consistent. Moreover, we define the composition-consistent hull of a solution ф as the smallest composition-consistent solution containing ф. The composition-consistent hulls of the Top cycle and Copeland solutions are specified, and we give some hints about the location of the hull of the Slater set. Concerning social choice functions, it is shown that Kemeny, Borda and Minimax social choice functions are not composition-consistent, whereas the Paretian one is composition-consistent. Moreover, we prove that the latter is the composition-consistent hull of the Borda and Minimax functions.

Condorcet choice correspondences: A set-theoretical comparison

Abstract In this paper we provide a set-theoretical comparison of the Condorcet choice correspondences discussed in the literature. We review the results on that issue and state some open problems.

Approval voting: three examples

In this paper we discuss three examples of approval voting games. The first one illustrates that a stronger solution concept than perfection is needed for a strategic analysis of this type of games. The second example shows that sophisticated voting can imply that the Condorcet winner gets no vote. The third example shows the possibility of insincere voting being a stable equilibrium.

Aggregation of preferences with a variable set of alternatives

Abstract. A social choice correspondence called the Essential set is studied with the help of an axiom called Cloning Consistency. Cloning consistency is the requirement that the formal choice rule be insensitive to the replication of alternatives. The Essential set is the support of the optimal mixed strategies in a symmetric two-party electoral competition game.

Strategic Vote Choice in One-Round and Two-Round Elections: An Experimental Study

The authors test a model of strategic vote choice in which the decision to support or not to support a candidate depends on the benefit associated with the election of a given candidate and the candidate’s perceived viability. They test the model with data collected in a series of experiments in which the participants voted in eight successive elections, four in one round and four in two rounds. Results show that the same model applies to both voting systems, although the impact of perceived viability is slightly weaker in two-round elections. The authors conclude that strategic considerations are almost as important in two-round as in one-round elections.

Interpretation of electoral mixed strategies

Abstract. In this paper is remarked that “mixed” strategies in games of electoral competition do not need to be interpreted as random moves. There are two a priori symmetric parties, and a finite (non spatial) set of alternatives. Parties are allowed to take unclear positions, by campaining on a “platform” that is a mix of several alternatives. Each individual nevertheless identifies a party with a single alternative, the number of individuals who identify a party with a given alternative being proportional to the importance of that alternative in the party’s platform.