Endogenous selection of aspiring and rational rules in coordination games

The paper studies an evolutionary model where players from a given population are randomly matched in pairs each period to play a co- ordination game. At each instant, a player can choose to adopt one of the two possible behavior rules, called the rational rule and the as- piring rule, and then take actions prescribed by the chosen rule. The choice between the two rules depends upon their relative performance in the immediate past. We show that there are two stable long run outcomes where either the rational rule becomes extinct and all play- ers in the population achieve full eciency, or that both the behavior rules co-exist and there is only a partial use of ecient strategies in the population. These ndings support the use of the aspiration driven behavior in several existing studies and also help us take a comparative evolutionary look at the two rules in retrospect.Co-evolution, Aspirations, Best-response, Random matching, Coordination games

Endogenous Selection of Aspiring and Rational rules in Coordination Games

The paper studies an evolutionary model where players from a given population are randomly matched in pairs each period to play a co-ordination game. At each instant, a player can choose to adopt one of the two possible behavior rules, called the rational rule and the aspiring rule, and then take actions prescribed by the chosen rule. The choice between the two rules depends upon their relative performance in the immediate past. We show that there are two stable long run outcomes where either the rational rule becomes extinct and all players in the population achieve full eciency, or that both the behavior rules co-exist and there is only a partial use of ecient strategies in the population. These ndings support the use of the aspiration driven behavior in several existing studies and also help us take a comparative evolutionary look at the two rules in retrospect.

Electoral Competition in 2-Dimensional Ideology Space with Unidimensional Commitment

We study a model of political competition between two candidates with two orthogonal issues, where candidates are office motivated and committed to a particular position in one of the dimensions, while having the freedom to slect (credibly) any position on the other dimension. We analyse two settings: a homogeneous one, where both candidates are committed to the same dimension and a heterogeneous one, where each candidate is committed to a different dimension. We characterise and give necessary and sufficient conditions for existence of convergent and divergent Nash equilibria for distributions with a non-empty and an empty core. We identify a special point on the ideology space whcih we call a strict median, existence of which is strictly related to existence of divergent Nash equilibria. A central conclusion of our anlysis is that for divergent equilibria, strong extremism (or differentiation) seems to be an important equlibrium feature.

The Hotelling-Downs Model with Runoff Voting

We consider the Hotelling-Downs model with n >= 2 oce seeking candidates and runo voting. We show that Nash equilibria in pure strategies always exist and that there are typically multiple equilibria, both convergent (all candidates are located at the median) and divergent (candidates locate at distinct positions), though only divergent equilibria are robust to free entry. Moreover, two-policy equilibria exist under any distribution of voters' ideal policies, while equilibria with more than two policies exist generically but under restrictive conditions that we characterize. In this sense, our analysis suggests that two-policy equilibria are the most prominent outcomes.Downs, Free Entry, Runoff System, Equilibrium

A Location Game On Disjoint Circles

Two players are endowed with resources for setting up N locations on K identical circles, with N > K>= 1. The players alternately choose these locations (possibly in batches of more than one in each round) in order to secure the area closer to their locations than that of their rival's. They face a resource mobility constraint such that not all N locations can be placed in the rst round. The player with the highest secured area wins the game and otherwise the game ends in a tie. Earlier research has shown that for K = 1, the second mover always has a winning strategy in this game. In this paper we show that with K > 1, the second mover advantage disappears as in this case both players have a tying strategy. We also study a natural variant of this game where the resource mobility constraint is more stringent so that in each round each player chooses a single location where we show that the second mover advantage re-appears. We suggest some Nash equilibrium configurations of locations in both versions of the game.

Electoral Competition in 2-Dimensional Ideology Space with Unidimensional Commitment

We study a model of political competition between two candidates with two orthogonal issues, where candidates are office motivated and committed to a particular position in one of the dimensions, while having the freedom to select (credibly) any position on the other dimension. We analyse two settings: a homogeneous one, where both candidates are committed to the same dimension and a heterogeneous one, where each candidate is committed to a different dimension. We characterise and give necessary and suffcient conditions for existence of convergent and divergent Nash equilibria for distributions with a non-empty and an empty core. We identify a special point in the ideology space which we call a strict median, existence of which is strictly related to existence of divergent Nash equilibria. A central conclusion of our analysis is that for divergent equilibria, strong extremism (or differentiation) seems to be an important equilibrium feature

Endogenous selection of aspiring and rational rules in coordination games

The paper studies an evolutionary model where players from a given population are randomly matched in pairs each period to play a co- ordination game. At each instant, a player can choose to adopt one of the two possible behavior rules, called the rational rule and the as- piring rule, and then take actions prescribed by the chosen rule. The choice between the two rules depends upon their relative performance in the immediate past. We show that there are two stable long run outcomes where either the rational rule becomes extinct and all play- ers in the population achieve full eciency, or that both the behavior rules co-exist and there is only a partial use of ecient strategies in the population. These ndings support the use of the aspiration driven behavior in several existing studies and also help us take a comparative evolutionary look at the two rules in retrospect

Endogenous selection of aspiring and rational rules in coordination games

The paper studies an evolutionary model where players from a given population are randomly matched in pairs each period to play a co- ordination game. At each instant, a player can choose to adopt one of the two possible behavior rules, called the rational rule and the as- piring rule, and then take actions prescribed by the chosen rule. The choice between the two rules depends upon their relative performance in the immediate past. We show that there are two stable long run outcomes where either the rational rule becomes extinct and all play- ers in the population achieve full eciency, or that both the behavior rules co-exist and there is only a partial use of ecient strategies in the population. These ndings support the use of the aspiration driven behavior in several existing studies and also help us take a comparative evolutionary look at the two rules in retrospect

Voronoi game on disjoint open curves

Two players are endowed with resources for setting up N locations on K open curves of identical lengths, with N > K greater than or equal to 1. The players alternately choose these locations (possibly in batches of more than one in each round) in order to secure the area closer to their locations than that of their rival's. The player with the highest secured area wins the game and otherwise the game ends in a tie. Earlier research has shown that, if an analogical game is played on disjoint closed curves, the second mover advantage is in place only if K = 1, while for K > 1 both players have a tying strategy. It was also shown that this results hold for open curves of identical lengths when rules of the game additionally require players to take exactly one location in the rst round. In this paper we show that the second mover advantage is still in place for K greater than or equal to 1 and 2K -1 less than or equal to N, even if the additional restriction is dropped, while K is less than or euqal to N <2K -1 results in the first mover advantage. We also study a natural variant of the game, where the resource mobility constraint is more stringent so that in each round each player chooses a single location and we show that the second mover advantage re-appears for K is less than or equal to N <2K -1 if K is an even number

Electoral Competition amongst Citizen-candidates and Downsian Politicians

In this paper we study a model of political competition where citizens vote sincerely and candidates may be either citizens or Downsian politicians. The model extends the citizen-candidate model proposed by Osborne and Slivinski [1996] by including Downsian politicians similar to those studied by Osborne [1993]. We give necessary and sufficient conditions for existence, together with complete characterisation, of one party and two party Nash equilibria in our model. An important feature, in view of the Duverger's Law, of the two-party equilibrium is that these equilibria cannot have any Downsian contestant. Moreover, we compare our model with that studied by Osborne and Slivinski [1996], showing that in both cases there exist po- litical configurations that can appear in one of the models only. We show also that in our settings it is possible to have Nash equilibria with Downsian candidates, without requiring to have very restrictive constraints on the dis- tribution function. We also argue that as the number of parties in equilibrium increases, the `likelihood' of an ideology driven citizen-candidate winning the elections and running the government falls. Finally we argue that in any equilibrium extremist parties proposing their policies uniquely are typically ideology-driven as well