scholarly journals Convergence and Quality of Iterative Voting Under Non-Scoring Rules

2017 ◽  
Author(s):  
Aaron Koolyk ◽  
Tyrone Strangway ◽  
Omer Lev ◽  
Jeffrey S. Rosenschein
Keyword(s):  
Social Choice ◽  
Empirical Analysis ◽  
Stated Preferences ◽  
Scoring Rules ◽  
Response Strategy ◽  
Voting Rules ◽  
Best Response ◽  
Voting Methods ◽  
Iterative Voting

Iterative voting is a social choice mechanism that assumes all voters are strategic, and allows voters to change their stated preferences as the vote progresses until an equilibrium is reached (at which point no player wishes to change their vote). Previous research established that this process converges to an equilibrium for the plurality and veto voting methods and for no other scoring rule. We consider iterative voting for non-scoring rules, examining the major ones, and show that none of them converge when assuming (as most research has so far) that voters pursue a best response strategy. We investigate other potential voter strategies, with a more heuristic flavor (since for most of these voting rules, calculating the best response is NP-hard); we show that they also do not converge. We then conduct an empirical analysis of the iterative voting winners for these non-scoring rules, and compare the winner quality of various strategies.

scholarly journals Convergence of Iterative Scoring Rules

2016 ◽  
Vol 57 ◽  
pp. 573-591 ◽  
Author(s):  
Omer Lev ◽  
Jeffrey S. Rosenschein
Keyword(s):  
Linear Order ◽  
Scoring Rules ◽  
Voting Systems ◽  
Choice Functions ◽  
Stable States ◽  
Voting Rules ◽  
Voting Rule ◽  
Social Choice Functions ◽  
Breaking Mechanism ◽  
Iterative Voting

In multiagent systems, social choice functions can help aggregate the distinct preferences that agents have over alternatives, enabling them to settle on a single choice. Despite the basic manipulability of all reasonable voting systems, it would still be desirable to find ways to reach plausible outcomes, which are stable states, i.e., a situation where no agent would wish to change its vote. One possibility is an iterative process in which, after everyone initially votes, participants may change their votes, one voter at a time. This technique, explored in previous work, converges to a Nash equilibrium when Plurality voting is used, along with a tie-breaking rule that chooses a winner according to a linear order of preferences over candidates. In this paper, we both consider limitations of the iterative voting method, as well as expanding upon it. We demonstrate the significance of tie-breaking rules, showing that no iterative scoring rule converges for all tie-breaking. However, using a restricted tie-breaking rule (such as the linear order rule used in previous work) does not by itself ensure convergence. We prove that in addition to plurality, the veto voting rule converges as well using a linear order tie-breaking rule. However, we show that these two voting rules are the only scoring rules that converge, regardless of tie-breaking mechanism.

scholarly journals Subset Selection Via Implicit Utilitarian Voting

2017 ◽  
Vol 58 ◽  
pp. 123-152 ◽  
Author(s):  
Ioannis Caragiannis ◽  
Swaprava Nath ◽  
Ariel D. Procaccia ◽  
Nisarg Shah
Keyword(s):  
Social Choice ◽  
Subset Selection ◽  
Voting Rules ◽  
For Profit ◽  
Design And Implementation ◽  
Ordinal Preferences ◽  
Not For Profit ◽  
Two Measures ◽  
Voting Methods ◽  
Latent Utility

How should one aggregate ordinal preferences expressed by voters into a measurably superior social choice? A well-established approach -- which we refer to as implicit utilitarian voting -- assumes that voters have latent utility functions that induce the reported rankings, and seeks voting rules that approximately maximize utilitarian social welfare. We extend this approach to the design of rules that select a subset of alternatives. We derive analytical bounds on the performance of optimal (deterministic as well as randomized) rules in terms of two measures, distortion and regret. Empirical results show that regret-based rules are more compelling than distortion-based rules, leading us to focus on developing a scalable implementation for the optimal (deterministic) regret-based rule. Our methods underlie the design and implementation of RoboVote.org, a not-for-profit website that helps users make group decisions via AI-driven voting methods.

A Political Economy Model of a Research University

2009 ◽  
pp. 132-143
Author(s):  
K. Sonin ◽  
I. Khovanskaya
Keyword(s):  
Organizational Structure ◽  
Information Structure ◽  
Research University ◽  
Hiring Decisions ◽  
Voting Rules ◽  
Economy Model ◽  
Trade Offs ◽  
Political Economic ◽  
Optimal Incentives

Hiring decisions are typically made by committees members of which have different capacity to estimate the quality of candidates. Organizational structure and voting rules in the committees determine the incentives and strategies of applicants; thus, construction of a modern university requires a political structure that provides committee members and applicants with optimal incentives. The existing political-economic model of informative voting typically lacks any degree of variance in the organizational structure, while political-economic models of organization typically assume a parsimonious information structure. In this paper, we propose a simple framework to analyze trade-offs in optimal subdivision of universities into departments and subdepartments, and allocation of political power.

Quality of Medical Care and Choice of Medical Treatment in Kenya: An Empirical Analysis

1993 ◽  
Vol 28 (4) ◽  
pp. 838 ◽  
Author(s):  
Germano Mwabu ◽  
Martha Ainsworth ◽  
Andrew Nyamete
Keyword(s):  
Medical Treatment ◽  
Medical Care ◽  
Empirical Analysis ◽  
Quality Of Medical Care

Computer simulations of voting systems

2000 ◽  
Vol 03 (01n04) ◽  
pp. 181-194 ◽  
Author(s):  
Dominique Lepelley ◽  
Ahmed Louichi ◽  
Fabrice Valognes
Keyword(s):  
Monte Carlo ◽  
Computer Simulations ◽  
Monte Carlo Methods ◽  
Scoring Rules ◽  
Voting Systems ◽  
Voting Rules ◽  
Asymptotic Case ◽  
Majority Principle ◽  
Voting Procedures ◽  
Democratic Principles

All voting procedures are susceptible to give rise, if not to paradoxes, at least to violations of some democratic principles. In this paper, we evaluate and compare the propensity of various voting rules -belonging to the class of scoring rules- to satisfy two versions of the majority principle. We consider the asymptotic case where the numbers of voters tends to infinity and, for each rule, we study with the help of Monte Carlo methods how this propensity varies as a function of the number of candidates.

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