We investigate the computational complexity of several decision problems in hedonic coalition formation games and demonstrate that attaining stability in such games remains NP-hard even when they are additive. Precisely, we prove that when either core stability or strict core stability is under consideration, the existence problem of a stable coalition structure is NP-hard in the strong sense. ...

Effectivity functions for finitely many players and alternatives are considered. It is shown that every monotonic and superadditive effectivity function can be augmented with equal chance lotteries to a finite lottery model—i.e., an effectivity function that preserves the original effectivity in terms of supports of lotteries—which has a Nash consistent representation. The latter means that the...

We show that feasible elimination procedures (Peleg, 1978) can be used to select k from m alternatives. An important advantage of this method is the core property: no coalition can guarantee an outcome that is preferred by all its members. We also provide an axiomatic characterization for the case k = 1, using the conditions of anonymity, Maskin monotonicity, and independent blocking. Finally, ...

This paper investigates algorithmic computability of simple games (voting games). It shows that (i) games with a finite carrier are computable, (ii) computable games have both finite winning coalitions and cofinite losing coalitions, and (iii) computable games violate any conceivable notion of anonymity, including finite anonymity and measurebased anonymity. The paper argues that computable gam...

We show, with an example, that the theorem on the characterization of the domains admitting strategy-proof and non-dictatorial social choice functions by Kalai and Muller (1977) does not hold when the set of alternatives is infinite. We consider two ways of overcoming this problem. The first identifies a set of domains admitting strategy-proof and non-dictatorial social choice functions when th...

We first provide the complete characterization of mechanisms that satisfy weak group strategy-proofness and queue-efficiency in the multiple machine queueing problem with two agents. For any such mechanism, there can be at most one point of discontinuity in the transfer map. We then state a necessary condition for mechanisms to satisfy queue-efficiency, weak group strategy-proofness and continu...

For many people “solidarity” has become a meaningless word used in slogans – too often used without leading to any economic consequences. We show in this paper conditions under which solidarity can be a powerful instrument. In a solidary action, an individual in a group contributes to a series of actions that aims for a reallocation of scarce resources. The willingness to contribute is mainly i...

We address the coordination problem of individuals deciding to join an association that provides a public good and selective benefits to its members, when ability of the association to fulfill its purposes depends on membership size. In a global game formulation, we show that a unique equilibrium with non-trivial membership exists, and we perform meaningful comparative statics. A unique equilib...

We characterize a class of collective choice rules such that collective preference relations are consistent. Consistency is a weakening of transitivity and a strengthening of acyclicity requiring that there be no cycles with at least one strict preference, which excludes the possibility of a “money pump.” The properties of collective choice rules used in our characterization are unrestricted do...

Seceral contingent caluation studies hace found that the open-ended format yields lower estimates of willingness to pay (WTP) than does the closed-ended, or dichotomous choice, format. In this study, WTP for a public encironmental good was estimated under four conditions: actual payment in response to open-ended and closed-ended requests, and hypothetical payment in response to open-ended and c...