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.

Deception Detection in a Computer-Mediated Environment: Gender, Trust, and Training Issues

The Department of Defense is increasingly relying on computer-mediated communications to conduct business. This reliance introduces an amplified vulnerability to strategic information manipulation, or deception. This research draws on communication and deception literature to develop a conceptual model proposing relationships between deception detection abilities in a computer-mediated environment, gender, trust, and training. An experiment was conducted with 119 communications personnel to test the proposed hypotheses. No relationship between gender or trust and deception detection accuracy was found. Partial support was found showing that training improves deception detection accuracy. The most significant finding was that individual’s deception detection abilities deteriorate in lean media environments. The results showed significant differences in deception detection abilities across media types; indicating lower accuracy rates in the lean media environments (i.e. audio and text). This suggests that deception detection is more difficult when the deceptive message is presented in a lean medium such as a text only online chat, than when delivered in richer medium. Future research should be conducted to further explore this finding

How to Defend a Network?

Modern economies rely heavily on their infrastructure networks. These networks face threats ranging from natural disasters to human attacks. As networks are pervasive, the investments needed to protect them are very large; this motivates the study of targeted defence. What are the ���key�� nodes to defend to maximize functionality of the network? What are the incentives of individual nodes to protect themselves in a networked environment and how do these incentives correspond to collective welfare? We provide a characterization of equilibrium attack and defence in terms of two classical concepts in graph theory ��� separators and transversals. We study the welfare costs of decentralized defence. We apply our results to the defence of the US Airport Network and the London Underground

Compellence: An Empirical Perspective

Compellence, the use of a contingent threat of force to get a target state to modify a behavior, is an understudied area of international relations. An empirical examination of this area reveals patterns of the frequency of attempted compellence and successful compellence that are not explained by current research or broader international relations theories. In the post-World War II period (1946–2001), the pattern is a rapid drop and continued suppression of success, but a continuation of compellence attempts at the historic level. Existing compellence research and international relations theory do not explain this puzzling disparity of low success and continued attempts at compellence. By comparing this pattern with a sample of the previous conditions (1914–1945), this study provides initial findings about the compellence puzzle. Key among them is the effects of the shift in the international system after World War II, the American policy of containment, norm formation and promulgation, shifts of compellence from the core to the periphery, and the domestic effects of compellence on the longevity of leaders

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