Issofa Moyouwou

• PhD
• Professor (Associate) at University of Yaoundé I

We propose a model of political competition and stability in nominally democratic societies characterized by fraudulent elections. In every election, an opposition candidate faces off against the current leader. If the incumbent wins, he continues to hold office, automatically positioning him as the candidate for the next election since there are n...

Given a nonempty set of voters and a nonempty set of candidates, we provide a characterization of preference domains over which the plurality rule is Condorcet consistent; these are preference domains over which it is possible to design a social choice function that always chooses a plurality winner and also respects the Condorcet criterion. We tak...

We address the problem of electing a committee subject to diversity constraints. Given a set of candidates and a set of voters, such that each voter is represented by a linear order, the goal is to select a fixed-size subset of candidates by combining the excellence of candidates and a given form of diversity requirements. The grounding assumption...

We study the relationships between two well-known social choice concepts, namely the principle of social acceptability introduced by Mahajne and Volij (Soc Choice Welf 51(2):223–233, 2018), and the majoritarian compromise rule introduced by Sertel (Lectures notes in microeconomics, Bogazici University, 1986) and studied in detail by Sertel and Yılm...

We study the relationships between two well-known social choice concepts, namely the principle of social acceptability introduced by Mahajne and Volij (2018), and the majoritarian compromise rule introduced by Sertel (1986) and studied in detail by Sertel and Yılmaz (1999). The two concepts have been introduced separately in the literature in the s...

In a weighted voting game, each voter has a given weight, and a coalition of voters is successful if the sum of their individual weights exceeds a given quota. Such voting systems translate the idea that voters are not all equal by assigning them different weights. In such a situation, two voters are symmetric in a game if interchanging the two vot...

Power indices are methods for numerical evaluation of players’ voting power in simple (voting) games. We present alternative characterizations of the well-known Holler–Packel index, also known as the Public Good Index. To achieve this, we replace the Null Player Property, Anonymity and the Mergeability Condition with two new axioms. These axioms ar...

A social decision rule (SDR) is any non-empty set-valued map that associates any profile of individual preferences with the set of (winning) alternatives. An SDR is Condorcet-consistent if it selects the set of Condorcet winners whenever this later is non-empty. We propose a characterization of Condorcet consistent SDRs with a set of minimal axioms...

For cost allocation problems with an existing set of indivisible public resources with heterogeneous individual needs and non-rivalry access, an axiomatization is provided for the allocation rule that proportionally charges agents for a given resource with respect to their counting liability indices. The main result we obtain holds in the class of...

The fact that voters can manipulate election outcomes by misrepresenting their true preferences over competing political parties or candidates is commonly viewed as a major flaw of democratic voting systems. It is argued that insincere voting typically leads to suboptimal voting outcomes. This paper considers the problem of a mechanism designer who...

A monotonicity condition for multivariate real-valued functions is presented as a simple sufficient condition for Riemman integrability. The one dimension well-known result is extended to show that any monotone and bounded real-valued function on a bounded Jordan measurable subset of the n-cartesian product of the set R of real numbers is Riemann i...

Many interactions from linear production problems, financial markets, or sequencing problems are modeled by cooperative games where payoffs to a coalition of players is a random variable. For this class of cooperative games, we introduce a two-stage value as an ex-ante agreement among players. Players are first promised their prior Shapley shares w...

The Shapley–Shubik index is a specialization of the Shapley value and is widely applied to evaluate the power distribution in committees drawing binary decisions. It was generalized to decisions with more than two levels of approval both in the input and the output. The corresponding games are called (j, k) simple games. Here we present a new axiom...

Deriving a closed-form formula for the exact number of integer solutions to a system of linear inequalities involving integer coefficients of bounded integer free variables and integer parameters as a function of parameters is a general problem encountered in various fields, especially in social choice theory when analyzing how frequent an event is...

In an election, individuals may sometimes abstain or report preferences that include ties among candidates. How abstention or ties within individual preferences impact the performances of voting rules is a natural question addressed in the literature. We reconsider this question with respect to one of the main characteristics of a voting rule: its...

A voting rule is said to be vulnerable to the truncation paradox if some voters may seek to bring about a more preferable outcome by listing only a part of their sincere rankings on the competing candidates rather than listing their entire preference rankings on all the competing candidates. For three-candidate elections and for large electorates,...

Over the past two decades, IAC probability calculation techniques have made substantial progress, particularly through methodological studies that have linked these calculations to their appropriate mathematical framework. We report on this progress by a brief description of the methods of calculation used in this field and by reviewing some of the...

This paper is dedicated to the measurement of (or lack of) electoral justice in the 2010 Electoral College using a methodology based on the expected influence of the vote of each citizen for three probability models. Our first contribution is to revisit and reproduce the results obtained by Owen (1975) for the 1960 and 1970 Electoral College. His w...

A situation in which a finite set of agents can obtain certain payoffs by cooperation can be described by a cooperative game with transferable utility, or simply a TU-game. In the literature, various models of games with restricted cooperation can be found, in which only certain subsets of the agent set are allowed to form. In this article, we cons...

The Shapley-Shubik index is a specialization of the Shapley value and is widely applied to evaluate the power distribution in committees drawing binary decisions. It was generalized to decisions with more than two levels of approval both in the input and the output. The corresponding games are called $(j,k)$ simple games. Here we present a new axio...

The Shapley-Shubik index is a specialization of the Shapley value and is widely applied to evaluate the power distribution in committees drawing binary decisions. It was generalized to decisions with more than two levels of approval both in the input and the output. The corresponding games are called $(j,k)$~simple games. Here we present a new axio...

The Shapley-Shubik index was designed to evaluate the power distribution in committee systems drawing binary decisions and is one of the most established power indices. It was generalized to decisions with more than two levels of approval in the input and output. In the limit we have a continuum of options. For these games with interval decisions w...

Scoring elimination rules (SER), that give points to candidates according to their rank in voters’ preference orders and eliminate the candidate(s) with the lowest number of points, constitute an important class of voting rules. This class of rules, that includes some famous voting methods such as Plurality Runoff or Coombs Rule, suffers from a sev...

(Until September 23, 2017; a free copy is available at: https://authors.elsevier.com/a/1VVAobeCDscuM) Voting rule performances are sometimes evaluated according to their respective resistances to allow profitable misrepresentation of individual preferences. This seems to be a hard task when scoring systems with possibly non integer weights are invo...

Applying majority voting on a set of proposals may result in a series of decisions for which there exists a majority of voters who disagree with the collective decision in a majority of cases. This phenomenon is known as Anscombe’s paradox. In this paper, we provide new domains of individual opinions free of this paradox. To achieve this, we assume...

Analytical representations are developed for the probability that Approval Voting (AV) elects the Condorcet Loser in three-alternative elections with large electorates. A comparison of AV is then made to Plurality Rule (PR) to show that AV is much less susceptible to the risk of electing the Condorcet loser than PR. All calculations in this analysi...

Gehrlein et al (2013) have shown that an increase of the voters’ preference diversity, as measured by the number k of preference types in a voting situation, implies a decrease in the probability of having a Condorcet Winner. The results offered in this paper indicate that this relationship is far from being so clear when we consider instead the pr...

Metric rationalization of social decision rules have been intensively investigated when the social outcome is a nonempty subset of alternatives. The present paper proposes a similar framework for social welfare functions (SWFs) - that is when each social outcome is a ranking of alternatives. A metric rationalizable SWF reports as an approximation o...

According to a given quota q , a candidate a is beaten by another candidate b if at least a proportion of q individuals prefer b to a . The q -majority efficiency of a voting rule is the probability that the rule selects a candidate who is never beaten under the q -majority, given that such a candidate exits. Closed form representations are obtaine...

A Condorcet social choice procedure elects the candidate that beats every other candidate under simple majority when such a candidate exists. The reinforcement axiom roughly states that given two groups of individuals, if these two groups select the same alternative, then this alternative must also be selected by their union. Condorcet social choic...

According to a given quota q, a candidate a is beaten by another candidate b if at least a proportion of q individuals prefer b to a. The q-Condorcet efficiency of a voting rule is the probability that the rule selects a q-Condorcet winner (q-CW), that is any candidate who is never beaten under the q-majority. Closed form representations are obtain...

Voting rules are known to exhibit various paradoxical or problematic behaviors, typically in the form of their failure to meet the Condorcet criterion or in their vulnerability to strategic voting. Our basic premise is that a decrease in the number of coalitions of voters that exist with similar preference rankings should generally lead to a reduce...

It is well-kown that the (Aumann-Maschler) bargaining set of a transferable utility game (or simply a game) with less than five players coincides with the core of the game, provided that the core is nonempty. We show that this coincidence still holds for a superset of the core, the objection-free core which is the set of all imputations with no bar...

Usually strategic misrepresentation of preferences in order to manipulate social choice functions is studied under the standard common knowledge assumption. In this paper, we introduce the completely opposite hypothesis of manipulation under complete ignorance. Our goal is to give an answer to the following question : do there still exist any strat...

The description and the characterization of the (Aumann-Maschler) bargaining set are known, but its determination is still hard given a generic transferable utility cooperative game. We provide here an exhaustive determination of the bargaining set of any three-player game, balanced or not, superadditive or not.

Arrow’s theorem [1963] states that a social welfare function (SWF) that simultaneously satis.es completeness, transitivity, independence of irrelevant alternatives (IIA) and Pareto principle is necessarily dictatorial in the sense that the social decision on any pair of candidates coincides with the strict preference of a fixed individual, the Arro...

The reinforcement axiom roughly states that when an alternative is selected by two different constituencies, it must also be selected by their union. Hare and Coombs rules are special cases of sequential positional voting rules, which are known to violate this axiom. In this article, we first show that reinforcement can be violated by all such rule...

Intuitively, a voting rule satisfies the condition of positive association if it guarantees that an improvement for an alternative in the preferences expressed by voters results in a change, if there is any, of the social status of that alternative in the same direction. In this article, we consider two interpretations of this notion, and for parli...

It usually happens that the alternatives to be voted on in committees are chosen or sponsored by some particularly active committee members. For example, in parliaments, some representatives and some government members are known to be especially active in introducing bills on which the whole committee will later vote. It appears that parliamentary...

It usually happens that the alternatives to be voted on in committees are chosen or sponsored by some particularly active committee members. For example, in parliaments, some representatives and some government members are known to be especially active in introducing bills on which the whole committee will later vote. It appears that parliamentary...

In this paper we study the vulnerability of parliamentary voting procedures to strategic candidacy. Candidates involved in an election are susceptible to influence the outcome by opting out or opting in. In the context of three-alternative elections and under the impartial anonymous culture assumption, we evaluate the frequencies of such strategic...

In this paper we define manipulation with restricted beliefs as the possibility for some voter to have an insincere preference ordering that dominates the sincere one within the given individual beliefs over other agents' preferences. We then show that all non-dictatorial voting schemes are manipulable in this sense, up to a given threshold.

Under the impartial anonymous culture assumption (IAC), we evaluate the proportion of anonymous profiles at which the amendment and plurality voting procedures violate the property of independence of irrelevant alternatives (IIA). We also examine the relation to single-peakedness of preferences and election of a Condorcet winner.

It has been known for a long time that many binary voting rules can select a Pareto dominated outcome, that is an outcome such that there exists some other alternative which is preferred by every voter. In this paper, we show that some of these rules can select an outcome Pareto dominated in a much stronger sense. Furthermore, our main results are...

This note uncovers new properties of the von Neumann-Morgenstern solution in weak tournaments and majoritarian games. We propose a new procedure for the construction of choice sets from weak tournaments, based on dynamic stability criteria. The idea is to analyze dynamic versions of the tournament game introduced by Laffond, Laslier and Le Breton (...

It has been known for a long time that many binary voting rules can select a Pareto dominated outcome, that is an outcome such that there exists some other alternative which is preferred by every voter. In this paper, we show that some of these rules can select an outcome Pareto dominated in a much stronger sense. Furthermore, our main results are...

The information on some best alternative of some voter can decide an individual to misrepresent strategically his sincere preference under a plurality voting (simple majority rule). We characterize such informations and then deduce the minimal informations required to manipulate.

It usually happens that the alternatives to be voted on in committees are chosen or sponsored by some particularly active committee members. For example, in parliaments, some represen- tatives and some government members are known to be especially active in introducing bills on which the whole committee will later vote. It appears that binary seque...