A Note on Link Formation

In this note we study the endogenous formation of cooperation structures. According to several equilibrium concepts the full cooperation structure will form or some structure that is payoff-equivalent to the full cooperation structure. As a by-product we find a class of games in strategic form where several equilibrium concepts coincide.

Coalition Formation and Potential Games

In this paper we study the formation of coalition structures in situations described by a cooperative game. Players choose independently which coalition they want to join. The payoffs to the players are determined by an allocation rule on the underlying game and the coalition structure that results from the strategies of the players according to some formation rule. We study two well-known coalition structure formation rules. We show that for both formation rules there exists a unique component efficient allocation rule that results in a potential game and study the coalition structures resulting from potential maximizing strategy profiles.cooperative game;coalition formation;potential game;potential maximizer

Link Monotonic Allocation Schemes

A network is a graph where the nodes represent players and the links represent bilateral interaction between the players. A reward game assigns a value to every network on a fixed set of players. An allocation scheme specifies how to distribute the worth of every network among the players. This allocation scheme is link monotonic if extending the network does not decrease the payoff of any player. We characterize the class of reward games that have a link monotonic allocation scheme. Two allocation schemes for reward games are studied, the Myerson allocation scheme and the position allocation scheme, which are both based on allocation rules for communication situations. We introduce two notions of convexity in the setting of reward games and with these notions of convexity we characterize the classes of reward games where the Myerson allocation scheme and the position allocation scheme are link monotonic. As a by-product we find a characterization of the Myerson value and the position value on the class of reward games using potentials.network;reward game;monotonic allocation scheme

Average Convexity in Communication Situations

In this paper we study inheritance properties of average convexity in communication situations. We show that the underlying graph ensures that the graphrestricted game originating from an average convex game is average convex if and only if every subgraph associated with a component of the underlying graph is the complete graph or a star graph. Furthermore, we study inheritance of (average) convexity of the associated potential games.

Symmetric Convex Games and Stable Structures

We study the model of link formation that was introduced by Aumann and Myerson (1988) and focus on symmetric convex games with transferable utilities. We answer an open question in the literature by showing that in a specific symmetric convex game with six players a structure that results in the same payoffs as the full cooperation structure can be formed according to a subgame perfect Nash equilibrium.symmetric convex game;undirected graph;link formation;stable structures

The Monoclus of a Coalitional Game

The analysis of single-valued solution concepts for coalitional games with transferable utilities has a long tradition. Opposed to most of this literature we will not deal with solution concepts that provide payoffs to the players for the grand coalition only, but we will analyze allocation scheme rules, which assign payoffs to all players in all coalitions. We introduce four closely related allocation scheme rules for coalitional games. Each of these rules results in a population monotonic allocation scheme (PMAS) whenever the underlying coalitional game allows for a PMAS. The driving force behind these rules are monotonicities, which measure the payoff difference for a player between two nested coalitions. From a functional point of view these monotonicities can best be compared with the excesses in the definition of the (pre-)nucleolus. Two different domains and two different collections of monotonicities result in four allocation scheme rules. For each of the rules we deal with nonemptiness, uniqueness, and continuity, followed by an analysis of conditions for (some of) the rules to coincide. We then focus on characterizing the rules in terms of subbalanced weights. Finally, we deal with computational issues by providing a sequence of linear programs.cooperative game theory;population monotonic allocation schemes;allocation scheme rules

A One-Stage Model of Link Formation and Payoff Division

In this paper we introduce a strategic form model in which cooperation structures and divisions of the payoffs are determined simultaneously. We analyze the cooperation structures and payoff divisions that result according to several equilibrium concepts. We find that essentially no cycles will result and that a player need not profit from a central position in a cooperation structure.

Average Convexity in Communication Situations

In this paper we study inheritance properties of average convexity in communication situations. We show that the underlying graph ensures that the graphrestricted game originating from an average convex game is average convex if and only if every subgraph associated with a component of the underlying graph is the complete graph or a star graph. Furthermore, we study inheritance of (average) convexity of the associated potential games.

A Dual Egalitarian Solution

In this note we introduce an egalitarian solution, called the dual egalitarian solution, that is the natural counterpart of the egalitarian solution of Dutta and Ray (1989).We prove, among others, that for a convex game the egalitarian solution coincides with the dual egalitarian solution for its dual concave game.cooperative games;egalitarianism;duality