In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Evolution and the Theory of Games

Two-person Cooperative Games

Thermal physics: Second edition by C. B. P. Finn, Chapman and Hall, London-Glasgow-New York-Tokyo-Melbourne-Madras, 1993 physics and its applications series, volume 5, 256 pages price: ß13.95

EPJ E publishes papers describing advances in the understanding of physical aspects of Soft Matter and Biological Systems. The journal includes reports of experimental, computational and theoretical studies and appeals to the broad interdisciplinary communities including physics, chemistry, biology, mathematics and materials science. Unique features of EPJ E: Tips and tricks short papers focused on a novel methodological approach that enables new science Colloquia papers reviewing new directions in Research Prestigious international board of editors Highly competent and fast editorial handling Global contributions and global readership Commonly used title abbreviations: Eur. Phys. J. E, Eur.Phys.J.E, EPJE, EPJ E

The European Physical Journal D

The rapidly growing field of computational social choice, at the intersection of computer science and economics, deals with the computational aspects of collective decision making. This handbook, written by thirty-six prominent members of the computational social choice community, covers the field comprehensively. Chapters devoted to each of the field's major themes offer detailed introductions. Topics include voting theory (such as the computational complexity of winner determination and manipulation in elections), fair allocation (such as algorithms for dividing divisible and indivisible goods), coalition formation (such as matching and hedonic games), and many more. Graduate students, researchers, and professionals in computer science, economics, mathematics, political science, and philosophy will benefit from this accessible and self-contained book.

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Handbook of Computational Social Choice

It has often been claimed that the current allocation of votes among EU states is not fair. In this paper we verify this assertion by carrying out an evaluation of the distribution of power among the member states. The results show that the current distribution of votes for the qualified majority does not lead to a fair distribution of power whatever definition of the EU is considered. It can not be claimed however that the current voting process has a systematic bias in favor of certain states. We also present a simple method to derive voting weights which lead to a fair allocation of power.

Is the allocation of voting power among EU states fair

We provide a new axiomatization of the Shapley-Shubik and the Banzhaf power indices in the domain of simple superadditive games by means of transparent axioms. Only anonymity is shared with the former characterizations in the literature. The rest of the axioms are substituted by more transparent ones in terms of power in collective decision-making procedures. In particular, a clear restatement and a weaker alternative for the transfer axiom are proposed. Only one axiom differentiates the characterization of either index, and these differentiating axioms provide a new point of comparison. In a first step both indices are characterized up to a zero and a unit of scale. Then both indices are singled out by simple normalizing axioms.

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Shapley-Shubik and Banzhaf Indices Revisited

In this paper we propose a simple model for measuring ‘success’ or ‘decisiveness’ in voting situations. For an assessment of these features two inputs are claimed to be necessary: the voting rule and the voters’ behavior. The voting rule specifies when a proposal is to be accepted or rejected depending on the resulting vote configuration. Voting behavior is summarized by a distribution of probability over the vote configurations. This basic model provides a clear common conceptual basis for reinterpreting different power indices and some related game theoretic notions coherently from a unified point of view. Copyright Springer-Verlag 2005 (This abstract was borrowed from another version of this item.)

Assessing success and decisiveness in voting situations

The voting rule considered in this paper belongs to a large class of voting systems, called “range voting” or “utilitarian voting”, where each voter rates each candidate with the help of a given evaluation scale and the winner is the candidate with the highest total score. In approval voting the evaluation scale only consists of two levels: 1 (approval) and 0 (non approval). However non approval may mean disapproval or just indifference or even absence of sufficient knowledge for evaluating the candidate. In this paper we propose a characterization of a rule (that we refer to as dis&approval voting) that allows for a third level in the evaluation scale. The three levels have the following interpretation: 1 means approval, 0 means indifference, abstention or ‘do not know’, and \(-1\) means disapproval.

Dis&approval voting: a characterization

Every day thousands of decisions are made by all kinds of committees, parliaments, councils and boards by a 'yes-no' voting process. Sometimes a committee can only accept or reject the proposals submitted to it for a decision. On other occasions, committee members have the possibility of modifying the proposal and bargaining an agreement prior to the vote. In either case, what rule should be used if each member acts on behalf of a different-sized group? It seems intuitively clear that if the groups are of different sizes then a symmetric rule (e.g. the simple majority or unanimity) is not suitable. The question then arises of what voting rule should be used. Voting and Collective Decision-Making addresses this and other issues through a study of the theory of bargaining and voting power, showing how it applies to real decision-making contexts.

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Annick Laruelle

Papers

Is the allocation of voting power among EU states fair

Shapley-Shubik and Banzhaf Indices Revisited

Assessing success and decisiveness in voting situations

Dis&approval voting: a characterization

Voting and Collective Decision-Making