The Propensity to Disruption for Evaluating a Parliament

The issue of power plays a relevant role in evaluating the representativeness of a Parliament. In this paper a new governability index is introduced, taking inspiration from the propensity to disruption and referring to the power of the parties.Electoral system, representativeness, governability, simulation

Strategic Manipulations and Collusions in Knaster Procedure

The Knaster’s procedure is one of the simplest and most powerful mechanisms for allocating indivisible objects among agents requiring them, but its sealed bid feature may induce some agents in altering their valuations. In this paper we study the consequences of false declarations on the agents’ payoffs. A misrepresentation of a single agent could produce a gain or a loss. So, we analyze a possible behavior of a subset of infinitely risk-averse agents and propose how to obtain a safe gain via a joint misreporting of their valuations, regardless of the declarations of the other agents.Knaster’s procedure, misrepresentation, collusion

A game theoretic model for re-optimizing a railway timetable

The Setting In the Nineties of the last century the European Commission decided to open the railway market to competition, allowing different railway companies to operate on the same network. Under this framework Infrastructure Managers have to allocate capacity in order to define the timetable, dealing with possible slot conflicts between competing Transport Operators. The Problem An efficient train scheduling requires collecting a lot of information from the Transport Operators, but it may not be in their interests to reveal their private information. Therefore, it may be useful for real-world applications to design methods that provide incentives to Transport Operators for cooperating with the aim of increasing their utility; moreover, this may result in an improvement of the efficiency even for the Infrastructure Managers, so they also have incentives for favouring the cooperation. The Proposal In this paper we propose a game theoretical model in which the agents (Transport Operators) exchange information on their needs and are compensated by a possible increasing of their utility. This approach represents the situation as a coalition formation problem. In particular, we refer to the C-Solution proposed by Gerber (Rev Econ Design 5:149–175, 1), which is applied to some examples, each with different features. This model requires that information is revealed to a small number of competitors. This is rather important in a market currently still characterized by operator reluctance to an indiscriminate diffusion of information. Furthermore, the low dimension of the problem allows having a low computational complexity

Orders of Criticality in Voting Games

The authors focus on the problem of investigating the blackmail power of players in simple games, which is the possibility of players of threatening coalitions to cause them loss using arguments that are (apparently) unjustified. To this purpose, the classical notion of the criticality of players has been extended, in order to characterize situations where players may gain more power over the members of a coalition thanks to collusion with other players

On 1-convexity and nucleolus of co-insurance games

The situation, in which an enormous risk is insured by a number of insurance companies, is modeled through a cooperative TU game, the so-called co-insurance game, first introduced in Fragnelli and Marina (2004). In this paper we show that a co-insurance game possesses several interesting properties that allow to study the nonemptiness and the structure of the core and to construct an efficient algorithm for computing the nucleolus

A Lexicographic Public Good Ranking

In this paper, we consider the consistency of the desirability relation with the ranking of the players in a simple game provided by some well-known solutions, in particular the Public Good Index [12] and the criticality-based ranking [1]. We define a new ranking solution, the lexicographic Public Good ranking (LPGR), strongly related to the Public Good Index being rooted in the minimal winning coalitions of the simple game, proving that it is monotonic with respect to the desirability relation [15], when it holds. A suitable characterization of the LPGR solution is provided. Finally, we investigate the relation among the LPGR solution and the criticality-based ranking, referring to the dual game

Using coalitional games on biological networks to measure centrality and power of genes

Abstract Motivation: The interpretation of gene interaction in biological networks generates the need for a meaningful ranking of network elements. Classical centrality analysis ranks network elements according to their importance but may fail to reflect the power of each gene in interaction with the others. Results: We introduce a new approach using coalitional games to evaluate the centrality of genes in networks keeping into account genes' interactions. The Shapley value for coalitional games is used to express the power of each gene in interaction with the others and to stress the centrality of certain hub genes in the regulation of biological pathways of interest. The main improvement of this contribution, with respect to previous applications of game theory to gene expression analysis, consists in a finer resolution of the gene interaction investigated in the model, which is based on pairwise relationships of genes in the network. In addition, the new approach allows for the integration of a priori knowledge about genes playing a key function on a certain biological process. An approximation method for practical computation on large biological networks, together with a comparison with other centrality measures, is also presented. Contact: [email protected]

The Shapley Value in the Knaster Gain Game

In Briata, Dall'Aglio and Fragnelli (2012), the authors introduce a coopera- tive game with transferable utility for allocating the gain of a collusion among completely risk-averse agents involved in the fair division procedure introduced by Knaster (1946). In this paper we analyze the Shapley value (Shapley, 1953) of the game and propose its use as a measure of the players' attitude towards collusion. Furthermore, we relate the sign of the Shapley value with the ranking order of the players' evaluation, and show that some players in a given ranking will always deter collusion. Finally, we characterize the coalitions that maximize the gain from collusion, and suggest an ad-hoc coalition formation mechanism