An optimal feedback model to prevent manipulation behaviours in consensus under social network group decision making

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.A novel framework to prevent manipulation behaviour in consensus reaching process under social network group decision making is proposed, which is based on a theoretically sound optimal feedback model. The manipulation behaviour classification is twofold: (1) ‘individual manipulation’ where each expert manipulates his/her own behaviour to achieve higher importance degree (weight); and (2) ‘group manipulation’ where a group of experts force inconsistent experts to adopt specific recommendation advices obtained via the use of fixed feedback parameter. To counteract ‘individual manipulation’, a behavioural weights assignment method modelling sequential attitude ranging from ‘dictatorship’ to ‘democracy’ is developed, and then a reasonable policy for group minimum adjustment cost is established to assign appropriate weights to experts. To prevent ‘group manipulation’, an optimal feedback model with objective function the individual adjustments cost and constraints related to the threshold of group consensus is investigated. This approach allows the inconsistent experts to balance group consensus and adjustment cost, which enhances their willingness to adopt the recommendation advices and consequently the group reaching consensus on the decision making problem at hand. A numerical example is presented to illustrate and verify the proposed optimal feedback model

The International Seabed and the Single Negotiating Text

This Article attempts to outline the events leading up to the submission of Part I of the Informal Single Negotiating Text by the Chairman of Committee I at the end of the Geneva session of the Conference, to examine the contents of that document, and to suggest some of the wider implications of developments regarding the international seabed area

Electoral Systems and Intra-Party Candidate Selection Processes: Influences on Legislators\u27 Behavior

How legislators behave and how cohesively parties act are influenced, to a great extent, by the institutional environment within which they operate. While most research has regarded each institution separately, this dissertation project seeks to theorize and to empirically examine the complex institutional context that affects legislators\u27 behavior and representation styles. I specifically shed light on how electoral systems and intra-party candidate selection processes, separately and in combination, influence how much legislators emphasize their unique individualistic behaviors at the expense of their parties\u27 collective unified reputations. I argue that electoral systems and candidate selection procedures conditionally structure the incentives and institutional environment within which a legislator operates. Chapter 2 presents a theoretical/conceptual distinction between electoral systems and intra-party candidate selection processes and critiques the current literature that usually amalgamates them into a single factor. I further justify this distinction by empirically showing the lack of a strong association between the two institutions. Chapter 3 presents my theory concerning the distinct and combined conditional effect of electoral systems and selection processes on legislators\u27 behavior. I support my assertions using party-level models that use Rice cohesion scores and Weighted Rice cohesion scores as outcome variables. Chapter 4 tests my theory using individual level analysis which uses the ideological distance of a legislator from the median position of his or her party as a measure of behavior. To this end, I have collected a number of unique data sets that include information about parties\u27 candidate selection processes, parties\u27 cohesion measures, and individual legislators\u27 ideological distances. Using these original data sets, I can support my theory concerning the conditional combined effect of electoral systems and intra-party candidate selection processes on legislators\u27 behavior. The incentives and constraints legislators face are more convoluted than scholars previously assumed

Collective decision-making with goals

Des agents devant prendre une décision collective sont souvent motivés par des buts individuels. Dans ces situations, deux aspects clés doivent être abordés : sélectionner une alternative gagnante à partir des voix des agents et s'assurer que les agents ne manipulent pas le résultat. Cette thèse étudie l'agrégation et la dimension stratégique des décisions collectives lorsque les agents utilisent un langage représenté de manière compacte. Nous étudions des langages de type logique : de la logique propositionnelle aux CP-nets généralisés, en passant par la logique temporelle linéaire (LTL). Notre principale contribution est l'introduction d'un cadre de vote sur les buts, dans lequel les agents soumettent des buts individuels exprimés comme des formules de la logique propositionnelle. Les fonctions d'agrégation classiques issues du vote, de l'agrégation de jugements et de la fusion de croyances sont adaptées et étudiées de manière axiomatique et computationnelle. Les propriétés axiomatiques connues dans la littérature sur la théorie du choix social sont généralisées à ce nouveau type d'entrée, ainsi que les problèmes de complexité visant à déterminer le résultat du vote. Une autre contribution importante est l'étude de l'agrégation des CP-nets généralisés, c'est-à-dire des CP-nets où la précondition de l'énoncé de préférence est une formule propositionnelle. Nous utilisons différents agrégateurs pour obtenir un classement collectif des résultats possibles. Grâce à cette thèse, deux axes de recherche sont ainsi reliés : l'agrégation des CP-nets classiques et la généralisation des CP-nets à des préconditions incomplètes. Nous contribuons également à l'étude du comportement stratégique dans des contextes de prise de décision collective et de théorie des jeux. Le cadre du vote basé sur les buts est de nouveau étudié sous l'hypothèse que les agents peuvent décider de mentir sur leur but s'ils obtiennent ainsi un meilleur résultat. L'accent est mis sur trois règles de vote majoritaires qui se révèlent manipulables. Par conséquent, nous étudions des restrictions à la fois sur le langage des buts et sur les stratégies des agents en vue d'obtenir des résultats de votes non manipulables. Nous présentons par ailleurs une extension stratégique d'un modèle récent de diffusion d'opinion sur des réseaux d'influence. Dans les jeux d'influence définis ici, les agents ont comme but des formules en LTL et ils peuvent choisir d'utiliser leur pouvoir d'influence pour s'assurer que leur but est atteint. Des solutions classiques telles que la stratégie gagnante sont étudiées pour les jeux d'influence, en relation avec la structure du réseau et les buts des agents. Enfin, nous introduisons une nouvelle classe de concurrent game structures (CGS) dans laquelle les agents peuvent avoir un contrôle partagé sur un ensemble de variables propositionnelles. De telles structures sont utilisées pour interpréter des formules de logique temporelle en temps alternés (ATL), grâce auxquelles on peut exprimer l'existence d'une stratégie gagnante pour un agent dans un jeu itéré (comme les jeux d'influence mentionnés ci-dessus). Le résultat principal montre qu'un CGS avec contrôle partagé peut être représenté comme un CGS avec contrôle exclusif. En conclusion, cette thèse contribue au domaine de la prise de décision collective en introduisant un nouveau cadre de vote basé sur des buts propositionnels. Elle présente une étude de l'agrégation des CP-nets généralisés et une extension d'un cadre de diffusion d'opinion avec des agents rationnels qui utilisent leur pouvoir d'influence. Une réduction du contrôle partagé à un contrôle exclusif dans les CGS pour l'interprétation des logiques du raisonnement stratégique est également proposée. Par le biais de langages logiques divers, les agents peuvent ainsi exprimer buts et préférences sur la décision à prendre, et les propriétés souhaitées pour le processus de décision peuvent en être garanties.Agents having to take a collective decision are often motivated by individual goals. In such scenarios, two key aspects need to be addressed. The first is defining how to select a winning alternative from the expressions of the agents. The second is making sure that agents will not manipulate the outcome. Agents should also be able to state their goals in a way that is expressive, yet not too burdensome. This dissertation studies the aggregation and the strategic component of multi-agent collective decisions where the agents use a compactly represented language. The languages we study are all related to logic: from propositional logic, to generalized CP-nets and linear temporal logic (LTL). Our main contribution is the introduction of the framework of goal-based voting, where agents submit individual goals expressed as formulas of propositional logic. Classical aggregation functions from voting, judgment aggregation, and belief merging are adapted to this setting and studied axiomatically and computationally. Desirable axiomatic properties known in the literature of social choice theory are generalized to this new type of propositional input, as well as the standard complexity problems aimed at determining the result. Another important contribution is the study of the aggregation of generalized CP-nets coming from multiple agents, i.e., CP-nets where the precondition of the preference statement is a propositional formula. We use different aggregators to obtain a collective ordering of the possible outcomes. Thanks to this thesis, two lines of research are thus bridged: the one on the aggregation of complete CP-nets, and the one on the generalization of CP-nets to incomplete preconditions. We also contribute to the study of strategic behavior in both collective decision-making and game-theoretic settings. The framework of goal-based voting is studied again under the assumption that agents can now decide to submit an untruthful goal if by doing so they can get a better outcome. The focus is on three majoritarian voting rules which are found to be manipulable. Therefore, we study restrictions on both the language of the goals and on the strategies allowed to the agents to discover islands of strategy-proofness. We also present a game-theoretic extension of a recent model of opinion diffusion over networks of influence. In the influence games defined here, agents hold goals expressed as formulas of LTL and they can choose whether to use their influence power to make sure that their goal is satisfied. Classical solution concepts such as weak dominance and winning strategy are studied for influence games, in relation to the structure of the network and the goals of the agents. Finally, we introduce a novel class of concurrent game structures (CGS) in which agents can have shared control over a set of propositional variables. Such structures are used for the interpretation of formulas of alternating-time temporal logic, thanks to which we can express the existence of a winning strategy for an agent in a repeated game (as, for instance, the influence games mentioned above). The main result shows by means of a clever construction that a CGS with shared control can be represented as a CGS with exclusive control. In conclusion, this thesis provides a valuable contribution to the field of collective decision-making by introducing a novel framework of voting based on individual propositional goals, it studies for the first time the aggregation of generalized CP-nets, it extends a framework of opinion diffusion by modelling rational agents who use their influence power as they see fit, and it provides a reduction of shared to exclusive control in CGS for the interpretation of logics of strategic reasoning. By using different logical languages, agents can thus express their goals and preferences over the decision to be taken, and desirable properties of the decision process can be ensured

A new uniform voting system for elections to the European Parliament?

This thesis looks at the critical issue of electoral system reform relating to elections to the European Parliament. Directly elected since 1979, elections to the European Parliament operate on the basis of highly diverging national systems in the 27 member states, despite a mandate for electoral reform which should lead to a uniform system since the 1950s. The analysis of this thesis centres around the matters of legitimacy and the perceived democratic deficit, as surprisingly, there has been little or no discussion to date on the way the electoral system of elections to the European Parliament promotes or hinders the democratic legitimacy of the European Union. The European Union is conceptualised by the means of three different models, the EU as an international organisation, a supranational technocratic regime, and as a federal order. This thesis addresses the democratic deficit point by constructing an ideal type electoral system where it is currently lacking - in relation to a federal order. This research makes an interdisciplinary contribution by combining a value free positive political science on the one side and a normative legal approach on the other. Whereas a good deal of legal analysis is either explicitly based on a federal model of the European Union or implicitly premised on such an approach, detailed analysis of the implications of federalism for EU level democracy is much less common. Next to historic developments in the field of electoral reform in the European Parliament, the recent Duff Reports as well as the debates around them are analysed. The thesis concludes that an electoral system needs to generate competition between European parties on European matters and presents core elements of a draft European Elections Act, a new uniform voting system for elections to the European Parliament

The Spatial Analysis of Elections and Committees: Four Decades of Research

It has been more than thirty five years since the publication of Downs's (1957) seminal volume on elections and spatial theory and more than forty since Black and Newing (1951) offered their analysis of majority rule and committees. Thus, in response to the question "What have we accomplished since then?" it is not unreasonable to suppose that the appropriate answer would be "a great deal." Unfortunately, reality admits of only a more ambiguous response

No exit from the joint decision trap? Can German federalism reform itself?

The unique institutions that make up Germany's unitary federal state, long considered part of the country's post-war success story, are now generally perceived as a joint-decision trap impeding effective policy responses to new economic and demographic challenges at both levels of government. Nevertheless, a high-powered bicameral Commission set up in the fall of 2003 failed to reach agreement on constitutional reforms. The paper analyzes the misguided procedural and substantive choices that led to this failure, and it discusses the possibility of asymmetric constitutional solutions that might enhance the capacity for autonomous action at both levels. -- Die im internationalen Vergleich einmaligen Institutionen des unitarischen Bundesstaats erschienen lange as Element der deutschen Erfolgsgeschichte in der Nachkriegszeit. Heute erscheinen sie jedoch als Politikverflechtungsfalle, welche die Politik in Bund und Ländern an der Bewältigung der neuen ökonomischen und demographischen Herausforderungen hindert. Trotzdem gelang es einer im Herbst 2003 eingesetzten und politisch potent besetzten gemeinsamen Kommission von Bundestag und Bundesrat nicht, sich auf eine Verfassungsreform zu einigen. Der Text analysiert die prozeduralen und sachlichen Fehlentscheidungen, die das Scheitern erklären, und er erörtert die Möglichkeit asymmetrischer Lösungen, die den Spielraum für autonomes politisches Handeln auf beiden staatlichen Ebenen erweitern könnten.

Why Czech Parliamentary Party Groups Vote Less Unitedly. The Role of Frequent Voting and Big Majorities in Passing Bills

The article aims to explain voting unity in the Chamber of Deputies of the Parliament of the Czech Republic based on data from the years 1998-2002. It introduces the basic terminology & theoretical framework used in literature on the behaviour of parties in parliament & the basic institutional rules that should result in the unity of political parties in the Czech parliament. It then presents the data used to measure the unity of Czech parliamentary party groups. The initial assumption that specific institutional factors found in parliament & in political parties would lead to greater PPG unity in the Czech Republic was not confirmed. Although the institutional incentives are similar to those in Western European countries, they do not secure the same level of voting unity in Czech PPGs. The authors conclude that the relatively low party unity is caused by the size of the voting coalitions that pass individual bills