POLYTECHNICAL UNIVERSITY of MADRID Identification of Voting
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On the Distortion of Voting with Multiple Representative Candidates∗
The Thirty-Second AAAI Conference on Artificial Intelligence (AAAI-18) On the Distortion of Voting with Multiple Representative Candidates∗ Yu Cheng Shaddin Dughmi David Kempe Duke University University of Southern California University of Southern California Abstract voters and the chosen candidate in a suitable metric space (Anshelevich 2016; Anshelevich, Bhardwaj, and Postl 2015; We study positional voting rules when candidates and voters Anshelevich and Postl 2016; Goel, Krishnaswamy, and Mu- are embedded in a common metric space, and cardinal pref- erences are naturally given by distances in the metric space. nagala 2017). The underlying assumption is that the closer In a positional voting rule, each candidate receives a score a candidate is to a voter, the more similar their positions on from each ballot based on the ballot’s rank order; the candi- key questions are. Because proximity implies that the voter date with the highest total score wins the election. The cost would benefit from the candidate’s election, voters will rank of a candidate is his sum of distances to all voters, and the candidates by increasing distance, a model known as single- distortion of an election is the ratio between the cost of the peaked preferences (Black 1948; Downs 1957; Black 1958; elected candidate and the cost of the optimum candidate. We Moulin 1980; Merrill and Grofman 1999; Barbera,` Gul, consider the case when candidates are representative of the and Stacchetti 1993; Richards, Richards, and McKay 1998; population, in the sense that they are drawn i.i.d. from the Barbera` 2001). population of the voters, and analyze the expected distortion Even in the absence of strategic voting, voting systems of positional voting rules. -
A Treasury System for Cryptocurrencies: Enabling Better Collaborative Intelligence ⋆
A Treasury System for Cryptocurrencies: Enabling Better Collaborative Intelligence ? Bingsheng Zhang1, Roman Oliynykov2, and Hamed Balogun3 1 Lancaster University, UK [email protected] 2 Input Output Hong Kong Ltd. [email protected] 3 Lancaster University, UK [email protected] Abstract. A treasury system is a community controlled and decentralized collaborative decision- making mechanism for sustainable funding of the blockchain development and maintenance. During each treasury period, project proposals are submitted, discussed, and voted for; top-ranked projects are funded from the treasury. The Dash governance system is a real-world example of such kind of systems. In this work, we, for the first time, provide a rigorous study of the treasury system. We modelled, designed, and implemented a provably secure treasury system that is compatible with most existing blockchain infrastructures, such as Bitcoin, Ethereum, etc. More specifically, the proposed treasury system supports liquid democracy/delegative voting for better collaborative intelligence. Namely, the stake holders can either vote directly on the proposed projects or delegate their votes to experts. Its core component is a distributed universally composable secure end-to-end verifiable voting protocol. The integrity of the treasury voting decisions is guaranteed even when all the voting committee members are corrupted. To further improve efficiency, we proposed the world's first honest verifier zero-knowledge proof for unit vector encryption with logarithmic size communication. This partial result may be of independent interest to other cryptographic protocols. A pilot system is implemented in Scala over the Scorex 2.0 framework, and its benchmark results indicate that the proposed system can support tens of thousands of treasury participants with high efficiency. -
Game Theory and Democracy Homework Problems
Game Theory and Democracy Homework Problems PAGE 82 Challenge Problem: Show that any voting model (such as the Unit Interval Model or the Unit Square Model) which has a point symmetry always has a Condorcet winner for every election, namely the candidate who is closest to the point of symmetry! PAGE 93 Exercise: Show that if there are not any cycles of any length in the preferences of the voters, then there must be a Condorcet winner. (Don’t worry about making your proof rigorous, just convince yourself of this fact, to the point you could clearly explain your ideas to someone else.) PAGE 105 Exercise: Prove that the strongest chain strength of a chain from Candidate Y to Candidate X is 3. (If you can convince a skeptical friend that it is true, then that is a proof.) Exercise: Prove that it is never necessary to use a candidate more than once to find a chain with the strongest chain strength between two candidates. Hint: Show that whenever there is a loop, like the one shown in red Y (7) Z (3) W (9) Y (7) Z (3) W (11) X, we can consider a shortened chain by simply deleting the red loop Y (7) Z (3) W (11) X which is at least as strong as the original loop. Exercises: Prove that all of the chains above are in fact strongest chains, as claimed. Hint: The next figure, which has all of the information of the margin of victory matrix, will be useful, and is the type of figure you may choose to draw for yourself for other elections, from time to time. -
Computational Perspectives on Democracy
Computational Perspectives on Democracy Anson Kahng CMU-CS-21-126 August 2021 Computer Science Department School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 Thesis Committee: Ariel Procaccia (Chair) Chinmay Kulkarni Nihar Shah Vincent Conitzer (Duke University) David Pennock (Rutgers University) Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Copyright c 2021 Anson Kahng This research was sponsored by the National Science Foundation under grant numbers IIS-1350598, CCF- 1525932, and IIS-1714140, the Department of Defense under grant number W911NF1320045, the Office of Naval Research under grant number N000141712428, and the JP Morgan Research grant. The views and conclusions contained in this document are those of the author and should not be interpreted as representing the official policies, either expressed or implied, of any sponsoring institution, the U.S. government or any other entity. Keywords: Computational Social Choice, Theoretical Computer Science, Artificial Intelligence For Grandpa and Harabeoji. iv Abstract Democracy is a natural approach to large-scale decision-making that allows people affected by a potential decision to provide input about the outcome. However, modern implementations of democracy are based on outdated infor- mation technology and must adapt to the changing technological landscape. This thesis explores the relationship between computer science and democracy, which is, crucially, a two-way street—just as principles from computer science can be used to analyze and design democratic paradigms, ideas from democracy can be used to solve hard problems in computer science. Question 1: What can computer science do for democracy? To explore this first question, we examine the theoretical foundations of three democratic paradigms: liquid democracy, participatory budgeting, and multiwinner elections. -
An Optimal Single-Winner Preferential Voting System Based on Game Theory∗
An Optimal Single-Winner Preferential Voting System Based on Game Theory∗ Ronald L. Rivest and Emily Shen Abstract • The election winner is determined by a random- ized method, based for example on the use of We present an optimal single-winner preferential vot- ten-sided dice, that picks outcome x with prob- ing system, called the \GT method" because of its in- ability p∗(x). If there is a Condorcet winner x, teresting use of symmetric two-person zero-sum game then p∗(x) = 1, and no dice are needed. We theory to determine the winner. Game theory is not also briefly discuss a deterministic variant of GT, used to describe voting as a multi-player game be- which we call GTD. tween voters, but rather to define when one voting system is better than another one. The cast ballots The GT system, essentially by definition, is opti- determine the payoff matrix, and optimal play corre- mal: no other voting system can produce election sponds to picking winners optimally. outcomes that are liked better by the voters, on the The GT method is quite simple and elegant, and average, than those of the GT system. We also look works as follows: at whether the GT system has several standard prop- erties, such as monotonicity, consistency, etc. • Voters cast ballots listing their rank-order pref- The GT system is not only theoretically interest- erences of the alternatives. ing and optimal, but simple to use in practice; it is probably easier to implement than, say, IRV. We feel • The margin matrix M is computed so that for that it can be recommended for practical use. -
Instructor's Manual
The Mathematics of Voting and Elections: A Hands-On Approach Instructor’s Manual Jonathan K. Hodge Grand Valley State University January 6, 2011 Contents Preface ix 1 What’s So Good about Majority Rule? 1 Chapter Summary . 1 Learning Objectives . 2 Teaching Notes . 2 Reading Quiz Questions . 3 Questions for Class Discussion . 6 Discussion of Selected Questions . 7 Supplementary Questions . 10 2 Perot, Nader, and Other Inconveniences 13 Chapter Summary . 13 Learning Objectives . 14 Teaching Notes . 14 Reading Quiz Questions . 15 Questions for Class Discussion . 17 Discussion of Selected Questions . 18 Supplementary Questions . 21 3 Back into the Ring 23 Chapter Summary . 23 Learning Objectives . 24 Teaching Notes . 24 v vi CONTENTS Reading Quiz Questions . 25 Questions for Class Discussion . 27 Discussion of Selected Questions . 29 Supplementary Questions . 36 Appendix A: Why Sequential Pairwise Voting Is Monotone, and Instant Runoff Is Not . 37 4 Trouble in Democracy 39 Chapter Summary . 39 Typographical Error . 40 Learning Objectives . 40 Teaching Notes . 40 Reading Quiz Questions . 41 Questions for Class Discussion . 42 Discussion of Selected Questions . 43 Supplementary Questions . 49 5 Explaining the Impossible 51 Chapter Summary . 51 Error in Question 5.26 . 52 Learning Objectives . 52 Teaching Notes . 53 Reading Quiz Questions . 54 Questions for Class Discussion . 54 Discussion of Selected Questions . 55 Supplementary Questions . 59 6 One Person, One Vote? 61 Chapter Summary . 61 Learning Objectives . 62 Teaching Notes . 62 Reading Quiz Questions . 63 Questions for Class Discussion . 65 Discussion of Selected Questions . 65 CONTENTS vii Supplementary Questions . 71 7 Calculating Corruption 73 Chapter Summary . 73 Learning Objectives . 73 Teaching Notes . -
Consistent Approval-Based Multi-Winner Rules
Consistent Approval-Based Multi-Winner Rules Martin Lackner Piotr Skowron TU Wien University of Warsaw Vienna, Austria Warsaw, Poland Abstract This paper is an axiomatic study of consistent approval-based multi-winner rules, i.e., voting rules that select a fixed-size group of candidates based on approval bal- lots. We introduce the class of counting rules, provide an axiomatic characterization of this class and, in particular, show that counting rules are consistent. Building upon this result, we axiomatically characterize three important consistent multi- winner rules: Proportional Approval Voting, Multi-Winner Approval Voting and the Approval Chamberlin–Courant rule. Our results demonstrate the variety of multi- winner rules and illustrate three different, orthogonal principles that multi-winner voting rules may represent: individual excellence, diversity, and proportionality. Keywords: voting, axiomatic characterizations, approval voting, multi-winner elections, dichotomous preferences, apportionment 1 Introduction In Arrow’s foundational book “Social Choice and Individual Values” [5], voting rules rank candidates according to their social merit and, if desired, this ranking can be used to select the best candidate(s). As these rules are concerned with “mutually exclusive” candidates, they can be seen as single-winner rules. In contrast, the goal of multi-winner rules is to select the best group of candidates of a given size; we call such a fixed-size set of candidates a committee. Multi-winner elections are of importance in a wide range of scenarios, which often fit in, but are not limited to, one of the following three categories [25, 29]. The first category contains multi-winner elections aiming for proportional representation. -
Selecting the Runoff Pair
Selecting the runoff pair James Green-Armytage New Jersey State Treasury Trenton, NJ 08625 [email protected] T. Nicolaus Tideman Department of Economics, Virginia Polytechnic Institute and State University Blacksburg, VA 24061 [email protected] This version: May 9, 2019 Accepted for publication in Public Choice on May 27, 2019 Abstract: Although two-round voting procedures are common, the theoretical voting literature rarely discusses any such rules beyond the traditional plurality runoff rule. Therefore, using four criteria in conjunction with two data-generating processes, we define and evaluate nine “runoff pair selection rules” that comprise two rounds of voting, two candidates in the second round, and a single final winner. The four criteria are: social utility from the expected runoff winner (UEW), social utility from the expected runoff loser (UEL), representativeness of the runoff pair (Rep), and resistance to strategy (RS). We examine three rules from each of three categories: plurality rules, utilitarian rules and Condorcet rules. We find that the utilitarian rules provide relatively high UEW and UEL, but low Rep and RS. Conversely, the plurality rules provide high Rep and RS, but low UEW and UEL. Finally, the Condorcet rules provide high UEW, high RS, and a combination of UEL and Rep that depends which Condorcet rule is used. JEL Classification Codes: D71, D72 Keywords: Runoff election, two-round system, Condorcet, Hare, Borda, approval voting, single transferable vote, CPO-STV. We are grateful to those who commented on an earlier draft of this paper at the 2018 Public Choice Society conference. 2 1. Introduction Voting theory is concerned primarily with evaluating rules for choosing a single winner, based on a single round of voting. -
Chapter 3 Voting Systems
Chapter 3 Voting Systems 3.1 Introduction We rank everything. We rank movies, bands, songs, racing cars, politicians, professors, sports teams, the plays of the day. We want to know “who’s number one?” and who isn't. As a lo- cal sports writer put it, “Rankings don't mean anything. Coaches continually stress that fact. They're right, of course, but nobody listens. You know why, don't you? People love polls. They absolutely love ’em” (Woodling, December 24, 2004, p. 3C). Some rankings are just for fun, but people at the top sometimes stand to make a lot of money. A study of films released in the late 1970s and 1980s found that, if a film is one of the 5 finalists for the Best Picture Oscar at the Academy Awards, the publicity generated (on average) generates about $5.5 mil- lion in additional box office revenue. Winners make, on average, $14.7 million in additional revenue (Nelson et al., 2001). In today's inflated dollars, the figures would no doubt be higher. Actors and directors who are nominated (and who win) should expect to reap rewards as well, since the producers of new films are eager to hire Oscar-winners. This chapter is about the procedures that are used to decide who wins and who loses. De- veloping a ranking can be a tricky business. Political scientists have, for centuries, wrestled with the problem of collecting votes and moulding an overall ranking. To the surprise of un- 1 CHAPTER 3. VOTING SYSTEMS 2 dergraduate students in both mathematics and political science, mathematical concepts are at the forefront in the political analysis of voting procedures. -
General Conference, Universität Hamburg, 22 – 25 August 2018
NEW OPEN POLITICAL ACCESS JOURNAL RESEARCH FOR 2018 ECPR General Conference, Universität Hamburg, 22 – 25 August 2018 EXCHANGE EDITORS-IN-CHIEF Alexandra Segerberg, Stockholm University, Sweden Simona Guerra, University of Leicester, UK Published in partnership with ECPR, PRX is a gold open access journal seeking to advance research, innovation and debate PRX across the breadth of political science. NO ARTICLE PUBLISHING CHARGES THROUGHOUT 2018–2019 General Conference bit.ly/introducing-PRX 22 – 25 August 2018 General Conference Universität Hamburg, 22 – 25 August 2018 Contents Welcome from the local organisers ........................................................................................ 2 Mayor’s welcome ..................................................................................................................... 3 Welcome from the Academic Convenors ............................................................................ 4 The European Consortium for Political Research ................................................................... 5 ECPR governance ..................................................................................................................... 6 ECPR Council .............................................................................................................................. 6 Executive Committee ................................................................................................................ 7 ECPR staff attending ................................................................................................................. -
Math in Society
Math in Society Edition 1.1 Revision 3 Contents Voting Theory . 1 David Lippman Weighted Voting . 19 David Lippman Fair Division . 31 David Lippman Graph Theory . 49 David Lippman Scheduling . 79 David Lippman Growth Models . 95 David Lippman Finance . 111 David Lippman Statistics . 131 David Lippman, Jeff Eldridge, onlinestatbook.com Describing Data . 143 David Lippman, Jeff Eldridge, onlinestatbook.com Historical Counting Systems . 167 Lawrence Morales Solutions to Selected Exercises . 201 David Lippman Pierce College Ft Steilacoom Copyright © 2010 David Lippman This book was edited by David Lippman, Pierce College Ft Steilacoom Development of this book was supported, in part, by the Transition Math Project Statistics and Describing Data contain portions derived from works by: Jeff Eldridge, Edmonds Community College (used under CC-BY-SA license) www.onlinestatbook.com (used under public domain declaration) Historical Counting Systems derived from work by: Lawrence Morales, Seattle Central Community College (used under CC-BY-SA license) Front cover photo: Jan Tik, http://www.flickr.com/photos/jantik/, CC-BY 2.0 This text is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. You are free: to Share — to copy, distribute, display, and perform the work to Remix — to make derivative works Under the following conditions: Attribution. You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work). -
Electoral Institutions, Party Strategies, Candidate Attributes, and the Incumbency Advantage
Electoral Institutions, Party Strategies, Candidate Attributes, and the Incumbency Advantage The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Llaudet, Elena. 2014. Electoral Institutions, Party Strategies, Candidate Attributes, and the Incumbency Advantage. Doctoral dissertation, Harvard University. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:12274468 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Electoral Institutions, Party Strategies, Candidate Attributes, and the Incumbency Advantage A dissertation presented by Elena Llaudet to the Department of Government in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Political Science Harvard University Cambridge, Massachusetts April 2014 ⃝c 2014 - Elena Llaudet All rights reserved. Dissertation Advisor: Professor Stephen Ansolabehere Elena Llaudet Electoral Institutions, Party Strategies, Candidate Attributes, and the Incumbency Advantage Abstract In developed democracies, incumbents are consistently found to have an electoral advantage over their challengers. The normative implications of this phenomenon depend on its sources. Despite a large existing literature, there is little consensus on what the sources are. In this three-paper dissertation, I find that both electoral institutions and the parties behind the incumbents appear to have a larger role than the literature has given them credit for, and that in the U.S. context, between 30 and 40 percent of the incumbents' advantage is driven by their \scaring off” serious opposition.