Judgment aggregation rules based on minimization.

in Actes des Cinquièmes Journées Francophones Modèles Formel de l'Interaction (MFI 11) (2011, July 12), XIII

Many voting rules are based on some minimization principle. Likewise, in the field of logic-based knowledge representation and reasoning, many belief change or inconsistency handling operators also make ... [more ▼]

Many voting rules are based on some minimization principle. Likewise, in the field of logic-based knowledge representation and reasoning, many belief change or inconsistency handling operators also make use of minimization. Surprisingly, minimization has not played a major role in the field of judgment aggregation, in spite of its proximity to voting theory and logic-based knowledge representation and reasoning. Here we make a step in this direction and study six judgment aggregation rules; two of them, based on distances, have been previously defined; the other four are new, and all inspired both by voting theory and knowledge representation and reasoning. We study the inclusion relationships between these rules and address some of their social choice theoretic properties. [less ▲]

A Satisficing Agreements Model

in Proceedings of the 13th International Workshop on Coordination, Organization, Institutions and Norms (COIN@WI-IAT) (2011)

Satisficing, the concept proposed by Herbert Simon, as an approach to reaching agreements is little explored. We propose a model for satisficing agreement reaching for an adaptive collaborative group of ... [more ▼]

Satisficing, the concept proposed by Herbert Simon, as an approach to reaching agreements is little explored. We propose a model for satisficing agreement reaching for an adaptive collaborative group of agents. The group consists of one human agent familiar with the problem and arbitrarily many artificial agents. Our model raises to the team level the recognition-primed decision model constructed in the field of cognitive decision-making by using social choice for reaching group opinions. [less ▲]

Reliable Methods of Judgement Aggregation

in Journal of Logic and Computation (2010), 20(2), 603617

The aggregation of consistent individual judgements on logically interconnected propositions into a collective judgement on the same propositions has recently drawn much attention. Seemingly reasonable ... [more ▼]

The aggregation of consistent individual judgements on logically interconnected propositions into a collective judgement on the same propositions has recently drawn much attention. Seemingly reasonable aggregation procedures, such as propositionwise majority voting, cannot ensure an equally consistent collective conclusion. The literature on judgement aggregation refers to such a problem as the discursive dilemma. In this article we assume that the decision which the group is trying to reach is factually right or wrong. Hence, we address the question of how good various approaches are at selecting the right conclusion. We focus on two approaches: distance-based procedures and a Bayesian analysis. They correspond to group-internal and group external decision making, respectively. We compare those methods in a probabilistic model whose assumptions are subsequently relaxed. Our findings have two general implications for judgement aggregation problems: first, in a voting procedure, reasons should carry higher weight than the conclusion, and second, considering members of an advisory board to be highly competent is a better strategy than discounting their advice. [less ▲]

Aggregation problems and models: what comes first?

in Stadler, Friedrich (Ed.) The Present Situation in the Philosophy of Science (2010)

The aggregation of consistent individual judgments on logically interconnected propositions into a collective judgment on the same propositions has recently drawn attention in law, philosophy, economics ... [more ▼]

The aggregation of consistent individual judgments on logically interconnected propositions into a collective judgment on the same propositions has recently drawn attention in law, philosophy, economics and computer science. Despite the apparent simplicity of the problem, reasonable aggregation procedures, such as propositionwise majority voting, cannot ensure a consistent collective outcome. The literature on judgment aggregation has been influenced by earlier work in social choice theory. As preference aggregation investigated in social choice theory, judgment aggregation studies aggregation functions under specific conditions. These are derived from properties of the preference aggregation realm. In this paper we argue that judgment aggregation problems are intrinsically different from preference aggregation ones. Thus, imposing exogenous models and properties is detrimental to a deep understanding of the specificity of judgment aggregation. [less ▲]

Five guidelines for normative multiagent systems

in Proceedings of JURIX 2009 - The 22nd International Conference on Legal Knowledge and Information Systems (2009, December)

n this paper we introduce and discuss five guidelines for the use of normative systems in computer science. We adopt a multiagent systems perspective, because norms are used to coordinate, organize, guide ... [more ▼]

n this paper we introduce and discuss five guidelines for the use of normative systems in computer science. We adopt a multiagent systems perspective, because norms are used to coordinate, organize, guide, regulate or control interaction among distributed autonomous systems. They are derived from the computer science literature. From the so-called ‘normchange’ definition of the first workshop on normative multiagent systems in 2005 we derive the guidelines to motivate which definition of normative multiagent system is used, to make explicit why norms are a kind of (soft) constraints deserving special analysis, and to explain why and how norms can be changed at runtime. From the so-called ‘mechanism design’ definition of the second workshop on normative multiagent systems in 2007 we derive the guidelines to discuss the use and role of norms as a mechanism in a game-theoretic setting, and to clarify the role of norms in the multiagent system. [less ▲]

Normative systems in computer science. Ten guidelines for normative multiagent systems

in Normative Multi-agent Systems (2009)

In this paper we introduce and discuss ten guidelines for the use of normative systems in computer science. We adopt a multiagent sys- tems perspective, because norms are used to coordinate, organize ... [more ▼]

In this paper we introduce and discuss ten guidelines for the use of normative systems in computer science. We adopt a multiagent sys- tems perspective, because norms are used to coordinate, organize, guide, regulate or control interaction among distributed autonomous systems. The first six guidelines are derived from the computer science literature. From the so-called ‘normchange’ definition of the first workshop on nor- mative multiagent systems in 2005 we derive the guidelines to motivate which definition of normative multiagent system is used, to make explicit why norms are a kind of (soft) constraints deserving special analysis, and to explain why and how norms can be changed at runtime. From the so-called ‘mechanism design’ definition of the second workshop on nor- mative multiagent systems in 2007 we derive the guidelines to discuss the use and role of norms as a mechanism in a game-theoretic setting, clarify the role of norms in the multiagent system, and to relate the no- tion of “norm” to the legal, social, or moral literature. The remaining four guidelines follow from the philosophical literature: use norms also to resolve dilemmas, and in general to coordinate, organize, guide, regulate or control interaction among agents, distinguish norms from obligations, prohibitions and permissions, use the deontic paradoxes only to illustrate the normative multiagent system, and consider regulative norms in rela- tion to other kinds of norms and other social-cognitive computer science concepts. [less ▲]

A complete conclusion-based procedure for judgment aggregation

in Proceedings of the First International Conference on Algorithmic Decision Theory (ADT) (2009)

Judgment aggregation is a formal theory reasoning about how a group of agents can aggregate individual judgments on connected propositions into a collective judgment on the same propositions. Three ... [more ▼]

Judgment aggregation is a formal theory reasoning about how a group of agents can aggregate individual judgments on connected propositions into a collective judgment on the same propositions. Three procedures for successfully aggregating judgments sets are: premise-based procedure, conclusion-based procedure and distance-based merging. The conclusion-based procedure has been little investigated because it provides a way to aggregate the conclusions, but not the premises, thus it outputs an incomplete judgment set. The goal of this paper is to present a conclusion-based procedure outputting complete judgment sets. [less ▲]

Desirable Tie-breaking Rules in Collective Decision Making

in Annales du LAMSADE (2008)

Judgment aggregation (JA) studies how to aggregate individual judgments to form collective decisions. Examples are expert panels, legal courts, boards, and councils. The problems investigated in this new ... [more ▼]

Judgment aggregation (JA) studies how to aggregate individual judgments to form collective decisions. Examples are expert panels, legal courts, boards, and councils. The problems investigated in this new field are relevant and common to many situations. Nevertheless, the existing procedures are idealized and, likewise the related problems of preference aggregation in social choice theory, the field is plagued by impossibility theorems. In this paper, we extend standard JA in order to offer a more realistic framework and to escape the impossibility results. We propose to distinguish between abstainers and neutral judgment as well as to model the notion of confidence a group member may have in the decision rule by assigning to each criterion a normalized weight. We then show how this new framework may help us to avoid indecision in most cases. [less ▲]

Independence in judgment aggregation

in Proceedings of the Ninth International Meeting of the Society for Social Choice and Welfare, SCW'08 (2008)

One of the better studied properties for operators in judgment aggregation is independence, which essentially dictates that the collective judgment on one issue should not depend on the individual ... [more ▼]

One of the better studied properties for operators in judgment aggregation is independence, which essentially dictates that the collective judgment on one issue should not depend on the individual judgments given on some other issue(s) in the same agenda. Independence is a desirable property for various reasons, but unfortunately it is too strong, as, together with mild additional conditions, it implies dictatorship. We propose here a weakening of independence, named agenda separability and show that this property is discriminant, i.e., some judgment aggregation rules satisfy it, others do not. [less ▲]

Common Foundations for Belief Revision, Belief Merging and Voting

in Formal Models of Belief Change in Rational Agents (2007)

In this paper, we consider a number of different ways of reasoning about voting as a problem of conciliating contradictory interests. The mechanisms that do the reconciliation are belief revision and be ... [more ▼]

In this paper, we consider a number of different ways of reasoning about voting as a problem of conciliating contradictory interests. The mechanisms that do the reconciliation are belief revision and be- lief merging. By investigating the relationship between different voting strategies and their associated counterparts in revision theory, we find that whereas the counting mechanism of the voting process is more easily done at the meta-level in belief merging, it can be brought to the object level in base revision. In the former case, the counting can b e tweaked according to the aggregation procedure used, whereas in base revision, we can only rely on the notion of minimal change and hence the syntactical representation of the voters’ preferences plays a crucial part in the process. This highlights the similarities between the revi sion approaches on the one hand and voting on the other, but also opens up a numb er of interesting questions. [less ▲]