Transactions on Computational Collective Intelligence XXIII

The Italian Constitution allows different procedures for approving the laws. In this paper we analyze their “strength” correlating their higher or lower use with the “strength” of the government and of the Parliament, measured through two parameters, the governability and the fragmentation.

Applications of approval voting to political analyses are conducted. Polish 2015 presidential and parliamentary elections are considered. A question regarding voting by approval voting method was included in the voting polls. Experiments deal with polls over representative samples and give a possibility to predict a winner of the second round of presidential elections and those parliamentary coalitions which may be approved by groups of voters supporting the given parties.

We study the complexity of voter control and shift bribery problems under two parliament choosing rules, one based on the Plurality rule and one based on the Borda rule (considering both the case where there is a threshold a party needs to pass to enter the parliament, and the case where there is no such threshold). A parliament choosing rule is a function that given a preference profile of the voters (where each voter ranks political parties) outputs the fraction of seats each of the parties should receive in the parliament. We study the complexity of three problems, shift bribery, control by adding voters, and control by deleting voters, where some agent modifies the election in order to increase the fraction of the seats in parliament assigned to a given party. We show that in most cases these problems can be solved in polynomial time for our parliament choosing rules, but we also show several \({{\mathrm {NP}}}\)-hardness results (for the Borda-based rule, for the case where there is a threshold for entering the parliament).

We propose a method for identifying national interests in the European Parliament by comparing roll call vote results with MEPs’ expected ideological positions. We define a new measure – national shift index, corresponding to the magnitude of national delegation’s shift from the aggregate ideological position – which quantifies the influence of the national interest on the voting results. Using this measure, we identify issues characterized by strongest dominance of national factors and compare national delegations’ propensity to vote along national lines.

We consider a committee of principals who gather to vote whether or not to renew a fixed-term employment contract of an agent. The principals’ private preferences depend on the agent’s past performance and the voting outcome. We analyze two scenarios: One where all communication is prohibited and the other where the principals engage in a pre-vote deliberation.

We characterize the set of symmetric, responsive equilibria of the pure voting game and show that informative voting constitutes an equilibrium whenever the number of votes required for the reappointment is sufficiently high. We then establish that if the principals can communicate prior to casting the decisive ballots, truthful information sharing coincides with Nash equilibrium behavior. However, in contrast to the common conception, sometimes pre-vote deliberation may actually make the principals worse off. The underlying intuition is that absent deliberation, the principals are unable to coordinate their votes, and this may force the agent to perform at a level beyond that in the game with communication.

In this paper, we analyze some power indices that are well-defined in the social context where goods are public. We consider the following indices: Public Help index θ [1], Public Help index ξ [2], the König and Bräuninger index [3, 4], the Nevison index [5], and the Rae index [6]. This paper continues the earlier work on public good indices (see [2]). The aim of this paper is to compare several power indices, taking into account the various properties, rankings amongst players, and ranges of the power indices.

We investigate a wage bargaining between a union and a firm where the parties’ preferences are expressed by varying discount rates and the threat of the union is to be on go-slow instead of striking. First, we describe the attitude of the union as hostile or altruistic where a hostile union is on go-slow in every disagreement period and an altruistic union never threatens the firm and holds out in every disagreement period. Then we derive subgame perfect equilibria of the bargaining when the union’s attitude is determined exogenously. Furthermore, we determine necessary conditions for the equilibrium extreme payoffs of both parties independently of the union’s attitude and calculate the extreme payoffs for a particular case when the firm is at least as patient as the union.

The multitude of existing forms of business organization (e.g. limited liability company, private partnership, joint stock company, etc.) and the possibilities of relationships and interactions between them call for the need to recognise individual components of these forms as elements influencing the group decision-making process. Among the many possible ways to assess this impact are so-called power indices, including the implicit index proposed here as a means of measuring of power in reciprocal ownership structures.

In this paper the concepts of manipulation as strategic voting (misrepresentation of true preferences) and strategic nomination (by adding, or removing alternatives) are investigated. The connection between Arrow’s and Gibbard-Satterthwaite theorems is discussed from the viewpoint of dilemma between dictatorship and manipulability.

This paper deals with the concept of manipulation, understood as preference misrepresentation, in the light of the main theoretical results focusing on their practical significance. It also reviews some indices measuring the degree of manipulability of choice functions. Moreover, the results on complexity of manipulation as well as on safe manipulability are briefly touched upon.

Isbell (1956) introduced a class of homogeneous weighted majority games based on the Fibonacci sequence. In our paper, we generalize this approach to other homogeneous representations of weighted majority games in a suitable Fibonacci framework. We provide some properties of such representations.

A cooperative game consists of a set of players and a characteristic function that determines the maximal profit or minimal cost that each subset of players can get when they decide to cooperate, regardless of the actions of the rest of the players. The relationships among the players can modify their bargaining and therefore their payoffs. The model of cooperation structures in a game introduces a graph on the set of players setting their relations and in which its components indicate the groups of players that are initially formed. In this paper we define the core and the Weber set and the notion of convexity for this family of games.

A novel approach to a human centric support of a consensus reaching process in a group of agents who present their testimonies as individual fuzzy preference relations is proposed. The concept of a degree of consensus is used which is meant as the degree to which, for instance, most of important agents agree as to almost all of relevant options. The fuzzy majorities are equated with linguistic quantifiers and Zadeh’s calculus of linguistically quantified propositions is used. The new concepts of a consensory and dissensory agent is introduced. The authors’ approach of using linguistic data summaries for a comprehensive summarization of how the agents’ current testimonies look like is then employed for the consensory and dissensory agents to obtain suggestions to the agents on changes of specific preferences that could lead to a higher degree of consensus. An explicit inclusion of opinions of the consensory and dissensory agents is shown to be an important step towards a fairness type attitude of the moderator as opinions of all agents are accounted for.

Dynamics has puzzled researchers since long ago. Among them are Greek philosophers such as Zeno of Elea (about 490-425 BC) and Aristotle (384-322 BC). They pointed at the phenomenon that the world occurs to us in different states at different points in time. However, for the transition from a given physical state to another physical state, it is not always clear from the given physical state what will be different in the next state. For example, Zeno and Aristotle argue that at one specific instant in the physical world (a snapshot) a moving arrow cannot be distinguished from an arrow in rest, yet the next state for a moving arrow is different (e.g., Aristotle, 1931). What is it in this given state that is driving the change to a next state in one case but which apparently is absent in the other case? When no physical property can be found in the given original physical state that can explain this change, what other entity can be there to explain the change? Usually an entity that is not part of physical reality, and therefore cannot be sensed in any way, but still may bring about changes in the physical world, is called a ghost. If for a transition from a given physical state nothing physical can be found in this state that can explain what will be different in the next state, then it may seem that this change has to be attributed to a ghost or ghost-like entity or property in the original state.