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International audience ; Social choice theory is the field of scientific inquiry that studies the aggregation of individual preferences toward a collective choice. For example, social choice theorists— who hail from a range of different disciplines, including mathematics, economics, and political science—are interested in the design and theoretical evaluation of voting rules. Questions of social choice have stimulated intellectual thought for centuries. Over time, the topic has fascinated many a great mind, from the Marquis de Condorcet and Pierre-Simon de Laplace, through Charles Dodgson (better known as Lewis Carroll, the author of Alice in Wonderland), to Nobel laureates such as Kenneth Arrow, Amartya Sen, and Lloyd Shapley.

International audience ; Social choice theory is the field of scientific inquiry that studies the aggregation of individual preferences toward a collective choice. For example, social choice theorists— who hail from a range of different disciplines, including mathematics, economics, and political science—are interested in the design and theoretical evaluation of voting rules. Questions of social choice have stimulated intellectual thought for centuries. Over time, the topic has fascinated many a great mind, from the Marquis de Condorcet and Pierre-Simon de Laplace, through Charles Dodgson (better known as Lewis Carroll, the author of Alice in Wonderland), to Nobel laureates such as Kenneth Arrow, Amartya Sen, and Lloyd Shapley.

We provide exact relations giving the probability of individual and coalitional manipulation of three specific social choice functions (Borda rule, Copeland rule, Plurality rule) in three-alternative elections when the notion of self-selectivity is imposed. The results suggest that the Borda rule is more vulnerable to coalitional manipulation than the Copeland rule and the Plurality rule. However, Plurality rule seems to be more vulnerable to individual manipulability when the number of voters is greater than a certain threshold value. In addition, the probability of individual and coalitional manipulation tends to vanish significantly when the notion of selfs-electivity is imposed.

We provide exact relations giving the probability of individual and coalitional manipulation of three specific social choice functions (Borda rule, Copeland rule, Plurality rule) in three-alternative elections when the notion of self-selectivity is imposed. The results suggest that the Borda rule is more vulnerable to coalitional manipulation than the Copeland rule and the Plurality rule. However, Plurality rule seems to be more vulnerable to individual manipulability when the number of voters is greater than a certain threshold value. In addition, the probability of individual and coalitional manipulation tends to vanish significantly when the notion of selfs-electivity is imposed.

We provide exact relations giving the probability of individual and coalitional manipulation of three specific social choice functions (Borda rule, Copeland rule, Plurality rule) in three-alternative elections when the notion of self-selectivity is imposed. The results suggest that the Borda rule is more vulnerable to coalitional manipulation than the Copeland rule and the Plurality rule. However, Plurality rule seems to be more vulnerable to individual manipulability when the number of voters is greater than a certain threshold value. In addition, the probability of individual and coalitional manipulation tends to vanish significantly when the notion of selfs-electivity is imposed.

We provide exact relations giving the probability of individual and coalitional manipulation of three specific social choice functions (Borda rule, Copeland rule, Plurality rule) in three-alternative elections when the notion of self-selectivity is imposed. The results suggest that the Borda rule is more vulnerable to coalitional manipulation than the Copeland rule and the Plurality rule. However, Plurality rule seems to be more vulnerable to individual manipulability when the number of voters is greater than a certain threshold value. In addition, the probability of individual and coalitional manipulation tends to vanish significantly when the notion of selfs-electivity is imposed.

The techniques of social choice and game theory are increasingly being used to analyse concepts in political theory. Although these techniques may prove invaluable for teasing out contradictory formulations, puzzles and problems with traditional concepts, formal writers often begin their analysis with simplistic intuitive accounts rather than building on earlier traditions in analytic political theory. This is no more obvious than with the social-choice and game-theory analysis of rights and Freedoms. This paper reviews these approaches and demonstrates that by ignoring the grammar of rights and freedoms, social-choice and game-theory analysis goes wrong from the very beginning. Formal writers need to take more account of the history of their subject, as developed in the analytic theory tradition.

The techniques of social choice and game theory are increasingly being used to analyse concepts in political theory. Although these techniques may prove invaluable for teasing out contradictory formulations, puzzles and problems with traditional concepts, formal writers often begin their analysis with simplistic intuitive accounts rather than building on earlier traditions in analytic political theory. This is no more obvious than with the social-choice and game-theory analysis of rights and Freedoms. This paper reviews these approaches and demonstrates that by ignoring the grammar of rights and freedoms, social-choice and game-theory analysis goes wrong from the very beginning. Formal writers need to take more account of the history of their subject, as developed in the analytic theory tradition.

Computational Social Choice is an interdisciplinary research area involving Economics, Political Science, and Social Science on the one side, and Mathematics and Computer Science (including Artificial Intelligence and Multiagent Systems) on the other side. Typical computational problems studied in this field include the vulnerability of voting procedures against attacks, or preference aggregation in multi-agent systems. Parameterized Algorithmics is a subfield of Theoretical Computer Science seeking to exploit meaningful problem-specific parameters in order to identify tractable special cases of in general computationally hard problems. In this paper, we propose nine of our favorite research challenges concerning the parameterized complexity of problems appearing in this context.

Computational Social Choice is an interdisciplinary research area involving Economics, Political Science, and Social Science on the one side, and Mathematics and Computer Science (including Artificial Intelligence and Multiagent Systems) on the other side. Typical computational problems studied in this field include the vulnerability of voting procedures against attacks, or preference aggregation in multi-agent systems. Parameterized Algorithmics is a subfield of Theoretical Computer Science seeking to exploit meaningful problem-specific parameters in order to identify tractable special cases of in general computationally hard problems. In this paper, we propose nine of our favorite research challenges concerning the parameterized complexity of problems appearing in this context. This work is dedicated to Jianer Chen, one of the strongest problem solvers in the history of parameterized algorithmics, on the occasion of his 60th birthday. Keywords: NP-hard problems; parameterized complexity; fixed-parameter tractability; kernelization; exact algorithms; voting; decision making; cake cutting

International audience ; Collective decisions are everywhere: choosing central or local governments, selecting a candidate to hire for an open position, choosing a restaurant to share a dinner with some friends are examples of collective decision making situations. Social Choice provides a lot of methods which can help people making a decision in such situations. However, the diversity of these voting procedures and the mathematical background necessary to understand them can be seen as obstacles to the use of these methods in everyday situations by laypersons. We claim that information visualization techniques can help a lot the democratization of social choice, by providing people with some easily interpretable information and, in the end, helping them making informed collective decisions. In this paper, we present the Edge-Compressed Majority Graph, a technique dedicated to the visualization of the majority graph of a preference profile. Using an insight-based evaluation method, we show that this technique gives better results in conveying information about the preferences than other classical visualization techniques.

International audience ; Collective decisions are everywhere: choosing central or local governments, selecting a candidate to hire for an open position, choosing a restaurant to share a dinner with some friends are examples of collective decision making situations. Social Choice provides a lot of methods which can help people making a decision in such situations. However, the diversity of these voting procedures and the mathematical background necessary to understand them can be seen as obstacles to the use of these methods in everyday situations by laypersons. We claim that information visualization techniques can help a lot the democratization of social choice, by providing people with some easily interpretable information and, in the end, helping them making informed collective decisions. In this paper, we present the Edge-Compressed Majority Graph, a technique dedicated to the visualization of the majority graph of a preference profile. Using an insight-based evaluation method, we show that this technique gives better results in conveying information about the preferences than other classical visualization techniques.

International audience ; Collective decisions are everywhere: choosing central or local governments, selecting a candidate to hire for an open position, choosing a restaurant to share a dinner with some friends are examples of collective decision making situations. Social Choice provides a lot of methods which can help people making a decision in such situations. However, the diversity of these voting procedures and the mathematical background necessary to understand them can be seen as obstacles to the use of these methods in everyday situations by laypersons. We claim that information visualization techniques can help a lot the democratization of social choice, by providing people with some easily interpretable information and, in the end, helping them making informed collective decisions. In this paper, we present the Edge-Compressed Majority Graph, a technique dedicated to the visualization of the majority graph of a preference profile. Using an insight-based evaluation method, we show that this technique gives better results in conveying information about the preferences than other classical visualization techniques.

The primary hypothesis stated by this paper is that the use of social choice theory in Ambient Intelligence systems can improve significantly users satisfaction when accessing shared resources. A research methodology based on agent based social simulations is employed to support this hypothesis and to evaluate these benefits. The result is a six-fold contribution summarized as follows. Firstly, several considerable differences between this application case and the most prominent social choice application, political elections, have been found and described. Secondly, given these differences, a number of metrics to evaluate different voting systems in this scope have been proposed and formalized. Thirdly, given the presented application and the metrics proposed, the performance of a number of well known electoral systems is compared. Fourthly, as a result of the performance study, a novel voting algorithm capable of obtaining the best balance between the metrics reviewed is introduced. Fifthly, to improve the social welfare in the experiments, the voting methods are combined with cluster analysis techniques. Finally, the article is complemented by a free and open-source tool, VoteSim, which ensures not only the reproducibility of the experimental results presented, but also allows the interested reader to adapt the case study presented to different environments.

Social choice theory (SCT) deals with the aggregation of individual preferences in order to arrive at social preference orders, i.e. at the 'general will'. The present paper examines whether SCT could be regarded as a complete political theory. SCT is evaluated against seven criteria, proposed by Martha Nussbaum, that a political theory needs to fulfill in order to be regarded a complete political theory. These criteria are: understanding of material need; procedural justice; liberty and its worth; racial, ethnic and religious differences; gender and family; international relations; and moral psychology. The analysis showed that SCT is strong at problems of procedural justification, distributive justice and some problems of ethics. It is weaker on the issues of moral psychology, and justice between nations. It is neglectful concerning the issues of racial, ethnic and religious inequality, and issues of gender and family. The paper concludes that the SCT can have an important place within more comprehensive political theories, but cannot claim itself to be a complete political theory.