Pragmatics of Multiwinner Voting: Algorithms and Preference Data Analysis

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Understanding Distance Measures Among Elections

Author(s): Niclas Boehmer, Piotr Faliszewski, Rolf Niedermeier, Stanisław Szufa, Tomasz Wąs
Published in: Proceedings of the Thirty-First International Joint Conference on Artificial Intelligence (IJCAI), Issue 31st, 2022, Page(s) 102-108, ISBN 978-1-956792-00-3
Publisher: International Joint Conferences on Artificial Intelligence
DOI: 10.24963/ijcai.2022/15

Robustness of Greedy Approval Rules

Author(s): Piotr Faliszewski, Grzegorz Gawron, Bartosz Kusek
Published in: Proceedings of the 19th European Conference on Multiagent Systems (EUMAS), Issue 19th, 2022, Page(s) 116-133, ISBN 978-3-031-20614-6
Publisher: Springer, Cham
DOI: 10.1007/978-3-031-20614-6_7

The Price of Justified Representation

Author(s): Edith Elkind, Piotr Faliszewski, Ayumi Igarashi, Pasin Manurangsi, Ulrike Schmidt-Kraepelin, Warut Suksompong
Published in: Proceedings of the 36th AAAI Conference on Artificial Intelligence (AAAI), Issue 36th, 2022, Page(s) 4983-4990, ISBN 978-1-57735-876-3
Publisher: AAAI Press
DOI: 10.1609/aaai.v36i5.20429

Neighborhood Stability in Assignments on Graphs

Author(s): Haris Aziz, Grzegorz Lisowski, Mashbat Suzuki, Jeremy Vollen
Published in: Proceedings of the 24th International Conference on Autonomous Agents and Multiagent Systems, Issue 24th, 2025, Page(s) 2420--2422, ISBN 979-8-4007-1426-9
Publisher: ACM, IFAAMAS

Robustness of Participatory Budgeting Outcomes: Complexity and Experiments

Author(s): Niclas Boehmer, Piotr Faliszewski, Łukasz Janeczko, Andrzej Kaczmarczyk
Published in: 16th International Symposium on Algorithmic Game Theory (SAGT), Issue 16th, 2023, Page(s) 161-178, ISBN 978-3-031-43254-5
Publisher: Springer Nature
DOI: 10.1007/978-3-031-43254-5_10

Participatory Budgeting Project Strength via Candidate Control

Author(s): Piotr Faliszewski, Łukasz Janeczko, Dusan Knop, Jan Pokorny, Simon Schierreich, Mateusz Słuszniak, Krzysztof Sornat
Published in: Proceedings of the 24th International Conference on Autonomous Agents and Multiagent Systems, Issue 24th, 2025, Page(s) 2514--2516, ISBN 979-8-4007-1426-9
Publisher: ACM, IFAAMAS

Diversity, Agreement, and Polarization in Elections

Author(s): Piotr Faliszewski, Andrzej Kaczmarczyk, Krzysztof Sornat, Stanisław Szufa, Tomasz Wąs
Published in: Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence (IJCAI), Issue 32nd, 2023, Page(s) 2684-2692, ISBN 978-1-956792-03-4
Publisher: International Joint Conference on Artificial Intelligence
DOI: 10.24963/ijcai.2023/299

Participatory Budgeting Project Strength via Candidate Control

Author(s): Piotr Faliszewski, Łukasz Janeczko, Dušan Knop, Jan Pokorný, Šimon Schierreich, Mateusz Słuszniak, Krzysztof Sornat
Published in: Proceedings of the Thirty-Fourth International Joint Conference on Artificial Intelligence, Issue 34th, 2025, Page(s) 3821-3829, ISBN 978-1-956792-06-5
Publisher: International Joint Conferences on Artificial Intelligence Organization
DOI: 10.24963/ijcai.2025/425

Robust Committee Voting, or The Other Side of Representation

Author(s): Gregory Kehne, Ulrike Schmidt-Kraepelin, Krzysztof Sornat
Published in: Proceedings of the 26th ACM Conference on Economics and Computation, Issue 26th, 2025, Page(s) 1131-1151, ISBN 979-8-4007-1943-1
Publisher: ACM
DOI: 10.1145/3736252.3742676

Computing Efficient Envy-Free Partial Allocations of Indivisible Goods

Author(s): Robert Bredereck, Andrzej Kaczmarczyk, Junjie Luo, Bin Sun
Published in: Proceedings of the 24th International Conference on Autonomous Agents and Multiagent Systems, Issue 24th, 2025, Page(s) 390--398, ISBN 979-8-4007-1426-9
Publisher: ACM, IFAAMAS

Properties of Position Matrices and Their Elections

Author(s): Niclas Boehmer, Jin-Yi Cai, Piotr Faliszewski, Austen Z. Fan, Łukasz Janeczko, Andrzej Kaczmarczyk, Tomasz Wąs
Published in: Proceedings of the 37th AAAI Conference on Artificial Intelligence (AAAI), Issue 37th, 2023, Page(s) 5507-5514, ISBN 978-1-57735-880-0
Publisher: AAAI Press
DOI: 10.1609/aaai.v37i5.25684

Evaluation of Project Performance in Participatory Budgeting

Author(s): Niclas Boehmer, Piotr Faliszewski, Łukasz Janeczko, Dominik Peters, Grzegorz Pierczyński, Šimon Schierreich, Piotr Skowron, Stanisław Szufa
Published in: Proceedings of the Thirty-Third International Joint Conference on Artificial Intelligence, Issue 33rd, 2024, Page(s) 2678--2686, ISBN 978-1-956792-04-1
Publisher: International Joint Conferences on Artificial Intelligence

Discovering Consistent Subelections

Author(s): Łukasz Janeczko, Jérôme Lang, Grzegorz Lisowski, Stanisław Szufa
Published in: Proceedings of the 23rd International Conference on Autonomous Agents and Multiagent Systems, Issue 23rd, 2024, Page(s) 935-943, ISBN 978-1-4007-0486-4
Publisher: ACM Press, IFAAMAS

Participatory Budgeting: Data, Tools and Analysis

Author(s): Piotr Faliszewski, Jarosław Flis, Dominik Peters, Grzegorz Pierczyński, Piotr Skowron, Dariusz Stolicki, Stanisław Szufa, Nimrod Talmon
Published in: Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence (IJCAI), Issue 32nd, 2023, Page(s) 2667-2674, ISBN 978-1-956792-03-4
Publisher: International Joint Conference on Artificial Intelligence
DOI: 10.24963/ijcai.2023/297

Justifying Groups in Multiwinner Approval Voting

Author(s): Edith Elkind, Piotr Faliszewski, Ayumi Igarashi, Pasin Manurangsi, Ulrike Schmidt-Kraepelin, Warut Suksompong
Published in: 15th International Symposium on Algorithmic Game Theory (SAGT), 2022, Page(s) 472-489, ISBN 978-3-031-15714-1
Publisher: Springer Cham
DOI: 10.1007/978-3-031-15714-1_27

Efficient Algorithms for Electing Successive Committees

Author(s): Pallavi Jain, Andrzej Kaczmarczyk
Published in: Proceedings of the Thirty-Fourth International Joint Conference on Artificial Intelligence, Issue 34th, 2025, Page(s) 3916-3924, ISBN 978-1-956792-06-5
Publisher: International Joint Conferences on Artificial Intelligence Organization
DOI: 10.24963/ijcai.2025/436

Using Multiwinner Voting to Search for Movies

Author(s): Piotr Faliszewski, Grzegorz Gawron
Published in: Proceedings of the 19th European Conference on Multiagent Systems (EUMAS), Issue 19th, 2022, Page(s) 134-151, ISBN 978-3-031-20614-6
Publisher: Springer, Cham
DOI: 10.1007/978-3-031-20614-6_8

Single-Winner Voting with Alliances: Avoiding the Spoiler Effect

Author(s): Grzegorz Pierczyński, Stanisław Szufa
Published in: Proceedings of the 23rd International Conference on Autonomous Agents and Multi-Agent Systems (AAMAS), Issue 23rd, 2024, Page(s) 935-943, ISBN 978-1-4007-0486-4
Publisher: ACM, IFAAMAS

Guide to Numerical Experiments on Elections in Computational Social Choice

Author(s): Niclas Boehmer, Piotr Faliszewski, Łukasz Janeczko, Andrzej Kaczmarczyk, Grzegorz Lisowski, Grzegorz Pierczyński, Simon Rey, Dariusz Stolicki, Stanisław Szufa, Tomasz Wąs
Published in: Proceedings of the Thirty-Third International Joint Conference on Artificial Intelligence, Issue 33rd, 2024, Page(s) 7962--7970, ISBN 978-1-956792-04-1
Publisher: International Joint Conferences on Artificial Intelligence

Ties in Multiwinner Approval Voting

Author(s): Łukasz Janeczko, Piotr Faliszewski
Published in: Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence (IJCAI), Issue 32nd, 2023, Page(s) 2765-2773, ISBN 978-1-956792-03-4
Publisher: International Joint Conferences on Artificial Intelligence
DOI: 10.24963/ijcai.2023/308

Selecting Representative Bodies: An Axiomatic View

Author(s): Manon Revel, Niclas Boehmer, Rachael Colley, Markus Brill, Piotr Faliszewski, Edith Elkind
Published in: Proceedings of the 23rd International Conference on Autonomous Agents and Multi-Agent Systems (AAMAS), Issue 23rd, 2024, Page(s) 2701-2705, ISBN 978-1-4007-0486-4
Publisher: ACM, IFAAMAS

Aggregation of Continuous Preferences in One Dimension

Author(s): Alberto Del Pia, Dušan Knop, Alexandra Lassota, Krzysztof Sornat, Nimrod Talmon
Published in: Proceedings of the Thirty-Third International Joint Conference on Artificial Intelligence, Issue 33rd, 2024, Page(s) 2748--2756, ISBN 978-1-956792-04-1
Publisher: International Joint Conferences on Artificial Intelligence

An Experimental Comparison of Multiwinner Voting Rules on Approval Elections

Author(s): Piotr Faliszewski, Martin Lackner, Krzysztof Sornat, Stanisław Szufa
Published in: Proceedings of the Thirty-Second International Joint Conference on Artificial Intelligence (IJCAI), Issue 32nd, 2023, Page(s) 2675-2683, ISBN 978-1-956792-03-4
Publisher: International Joint Conference on Artificial Intelligence
DOI: 10.24963/ijcai.2023/298

Properties of the Mallows Model Depending on the Number of Alternatives: A Warning for an Experimentalist

Author(s): Niclas Boehmer, Piotr Faliszewski, Sonja Kraiczy
Published in: Proceedings of the 40th International Conference on Machine Learning (ICML), Issue 40th, 2023, Page(s) 202:2689-2711
Publisher: Proceedings of Machine Learning Research

Putting a Compass on the Map of Elections

Author(s): Niclas Boehmer, Robert Bredereck, Piotr Faliszewski, Rolf Niedermeier, Stanisław Szufa
Published in: Proceedings of the Thirtieth International Joint Conference on Artificial Intellilgence (IJCAI), Issue 30th, 2021, Page(s) 59-65, ISBN 978-0-9992411-9-6
Publisher: International Joint Conferences on Artificial Intelligence
DOI: 10.24963/ijcai.2021/9

The Complexity of Proportionality Degree in Committee Elections

Author(s): Łukasz Janeczko, Piotr Faliszewski
Published in: Proceedings of the 36th AAAI Conference on Artificial Intelligence (AAAI), Issue 36th, 2022, Page(s) 5092-5099, ISBN 978-1-57735-876-3
Publisher: AAAI Press
DOI: 10.1609/aaai.v36i5.20442

An O(loglog n)-Approximation for Submodular Facility Location

Author(s): Fateme Abbasi, Marek Adamczyk, Miguel Bosch-Calvo, Jarosław Byrka, Fabrizio Grandoni, Krzysztof Sornat, Antoine Tinguely
Published in: Proceedings of the 51st International Colloquium on Automata, Languages, and Programming, Issue 51st, 2024, Page(s) 5:1--5:20, ISBN 978-3-95977-322-5
Publisher: Schloss Dagstuhl – Leibniz-Zentrum für Informatik
DOI: 10.4230/lipics.icalp.2024.5

On Improving Resource Allocations by Sharing

Author(s): Robert Bredereck, Andrzej Kaczmarczyk, Junjie Luo, Rolf Niedermeier, Florian Sachse
Published in: Proceedings of the 36th AAAI Conference on Artificial Intelligence (AAAI), Issue 36th, 2022, Page(s) 4875-4883, ISBN 978-1-57735-876-3
Publisher: AAAI Press
DOI: 10.1609/aaai.v36i5.20416

Bribery Can Get Harder in Structured Multiwinner Approval Election

Author(s): Bartosz Kusek, Robert Bredereck, Piotr Faliszewski, Andrzej Kaczmarczyk, Duan Knop
Published in: Proceedings of the 22nd International Conference on Autonomous Agents and Multiagent Systems (AAMAS), Issue 22nd, 2023, Page(s) 1725-1733, ISBN 978-1-4503-9432-1
Publisher: ACM, IFAAMAS

Near-Tight Algorithms for the Chamberlin-Courant and Thiele Voting Rules

Author(s): Krzysztof Sornat, Virginia Vassilevska Williams, Yinzhan Xu
Published in: Proceedings of the Thirty-First International Joint Conference on Artificial Intelligence (IJCAI), Issue 31st, 2022, Page(s) 482-488, ISBN 978-1-956792-00-3
Publisher: International Joint Conferences on Artificial Intelligence
DOI: 10.24963/ijcai.2022/69

Selecting the Most Conflicting Pair of Candidates

Author(s): Théo Delemazure, Łukasz Janeczko, Andrzej Kaczmarczyk, Stanisław Szufa
Published in: Proceedings of the Thirty-Third International Joint Conference on Artificial Intelligence, Issue 33rd, 2024, Page(s) 2766--2773, ISBN 978-1-956792-04-1
Publisher: International Joint Conferences on Artificial Intelligence

When Votes Change and Committees Should (Not)

Author(s): Robert Bredereck, Till Fluschnik, Andrzej Kaczmarczyk
Published in: Proceedings of the Thirty-First International Joint Conference on Artificial Intelligence (IJCAI), Issue 31st, 2022, Page(s) 144-150, ISBN 978-1-956792-00-3
Publisher: International Joint Conferences on Artificial Intelligence
DOI: 10.24963/ijcai.2022/21

Nonparametric Detection of Gerrymandering in Multiparty Plurality Elections

Author(s): Dariusz Stolicki, Wojciech Słomczyński, Stanisław Szufa
Published in: Proceedings of the Thirty-Third International Joint Conference on Artificial Intelligence, Issue 33rd, 2024, Page(s) 2967--2975, ISBN 978-1-956792-04-1
Publisher: International Joint Conferences on Artificial Intelligence

Fine-Grained Liquid Democracy for Cumulative Ballots

Author(s): Matthias Köppe, Martin Koutecký, Krzysztof Sornat, Nimrod Talmon
Published in: Proceedings of the 23rd International Conference on Autonomous Agents and Multi-Agent Systems, Issue 23rd, 2024, Page(s) 1029-1037, ISBN 978-1-4007-0486-4
Publisher: ACM, IFAAMAS

The Complexity of Subelection Isomorphism Problems

Author(s): Piotr Faliszewski, Krzysztof Sornat, Stanisław Szufa
Published in: Proceedings of the 36th AAAI Conference on Artificial Intelligence (AAAI), Issue 36th, 2022, Page(s) 4991-4998, ISBN 978-1-57735-876-3
Publisher: AAAI Press
DOI: 10.1609/aaai.v36i5.20430

Strategic Cost Selection in Participatory Budgeting

Author(s): Piotr Faliszewski, Łukasz Janeczko, Andrzej Kaczmarczyk, Grzegorz Lisowski, Piotr Skowron, Stanisław Szufa
Published in: Proceedings of the 23rd International Conference on Autonomous Agents and Multiagent Systems, Issue 23rd, 2024, Page(s) 2255--2257, ISBN 978-1-4007-0486-4
Publisher: ACM Press, IFAAMAS

Expected Frequency Matrices of Elections: Computation, Geometry, and Preference Learning

Author(s): Niclas Boehmer, Robert Bredereck, Edith Elkind, Piotr Faliszewski, Stanisław Szufa
Published in: Proceedings of the 36th Conference on Neural Information Processing Systems (NeurIPS), Issue 36th, 2022, Page(s) 31347--31359, ISBN 9781713873129
Publisher: Curran Associates, Inc.

A Map of Diverse Synthetic Stable Roommates Instances

Author(s): Niclas Boehmer, Klaus Heeger, Stanislaw Szufa
Published in: Proceedings of the 22nd International Conference on Autonomous Agents and Multiagent Systems (AAMAS), Issue 22nd, 2023, Page(s) 1003-1011, ISBN 978-1-4503-9432-1
Publisher: ACM, IFAAMAS

A Quantitative and Qualitative Analysis of the Robustness of (Real-World) Election Winners

Author(s): Niclas Boehmer, Robert Bredereck, Piotr Faliszewski, Rolf Niedermeier
Published in: Proceedings of the Second ACM Conference on Equity and Access in Algorithms, Mechanisms, and Optimization (EAAMO), 2022, Page(s) Article 7, ISBN 978-1-4503-9477-2
Publisher: ACM Press
DOI: 10.1145/3551624.3555292

How to Sample Approval Elections?

Author(s): Stanisław Szufa, Piotr Faliszewski, Łukasz Janeczko, Martin Lackner, Arkadii Slinko, Krzysztof Sornat, Nimrod Talmon
Published in: Proceedings of the Thirty-First International Joint Conference on Artificial Intelligence (IJCAI), Issue 31st, 2022, Page(s) 496-502, ISBN 978-1-956792-00-3
Publisher: International Joint Conferences on Artificial Intelligence
DOI: 10.24963/ijcai.2022/71

Strategic Cost Selection in Participatory Budgeting

Author(s): Piotr Faliszewski, Łukasz Janeczko, Andrzej Kaczmarczyk, Grzegorz Lisowski, Piotr Skowron, Stanisław Szufa, Mateusz Szwagierczak
Published in: Proceedings of the 39th International Conference on Advances in Neural Information Processing Systems, Issue 39th, 2025, ISBN 979-8-3313-1438-5
Publisher: NeurIPS

Learning Real-Life Approval Elections

Author(s): Piotr Faliszewski, Łukasz Janeczko, Andrzej Kaczmarczyk, Marcin Kurdziel, Grzegorz Pierczyński, Stanisław Szufa
Published in: Proceedings of the 24th International Conference on Autonomous Agents and Multiagent Systems, Issue 24th, 2025, Page(s) 704--712, ISBN 979-8-4007-1426-9
Publisher: ACM, IFAAMAS

High-Multiplicity Fair Allocation Using Parametric Integer Linear Programming

Author(s): Robert Bredereck, Andrzej Kaczmarczyk, Dušan Knop, Rolf Niedermeier
Published in: Proceedings of the 26th European Conference on Artificial Intelligence (ECAI), Issue 26th, 2023, Page(s) 303-310, ISBN 978-1-64368-437-6
Publisher: IOS Press
DOI: 10.3233/faia230284

The Cost Perspective of Liquid Democracy: Feasibility and Control

Author(s): Shiri Alouf-Heffetz, Łukasz Janeczko, Grzegorz Lisowski, Georgios Papasotiropoulos
Published in: Proceedings of the AAAI Conference on Artificial Intelligence, Issue 39, 2025, Page(s) 13538-13546, ISSN 2374-3468
Publisher: Association for the Advancement of Artificial Intelligence (AAAI)
DOI: 10.1609/aaai.v39i13.33478

Improving Resource Allocations by Sharing in Pairs

Author(s): Robert Bredereck, Andrzej Kaczmarczyk, Junjie Luo, Rolf Niedermeier, Florian Sachse
Published in: Journal of Artificial Intelligence Research, Issue Vol. 78 (2023), 2023, Page(s) 1069-1109, ISSN 1076-9757
Publisher: Morgan Kaufmann Publishers, Inc.
DOI: 10.1613/jair.1.15001

How similar are two elections?

Author(s): Piotr Faliszewski, Piotr Skowron, Arkadii Slinko, Krzysztof Sornat, Stanisław Szufa, Nimrod Talmon
Published in: Journal of Computer and System Sciences, Issue 150, 2025, Page(s) 103632, ISSN 0022-0000
Publisher: Academic Press
DOI: 10.1016/j.jcss.2025.103632

Justifying groups in multiwinner approval voting

Author(s): Edith Elkind; Piotr Faliszewski; Ayumi Igarashi; Pasin Manurangsi; Ulrike Schmidt-Kraepelin; Warut Suksompong
Published in: Theoretical Computer Science, Issue Volume 969, 2023, Page(s) 114039, ISSN 0304-3975
Publisher: Elsevier BV
DOI: 10.1016/j.tcs.2023.114039

A Map of Diverse Synthetic Stable Matching Instances

Author(s): Niclas Boehmer, Klaus Heeger, Stanisław Szufa
Published in: Journal of Artificial Intelligence Research, Issue Vol. 79 (2024), 2024, Page(s) 1113-1166, ISSN 1076-9757
Publisher: Morgan Kaufmann Publishers, Inc.
DOI: 10.1613/jair.1.15213

A Complexity-Theoretic Analysis of Majority Illusion in Social Networks

Author(s): Umberto Grandi, Lawqueen Kanesh, Grzegorz Lisowski, M.S. Ramanujan, Paolo Turrini
Published in: Journal of Artificial Intelligence Research, Issue 83, 2025, Page(s) 26:1--26:37, ISSN 1076-9757
Publisher: Morgan Kaufmann Publishers, Inc.
DOI: 10.1613/jair.1.17741

Distances Between Top-Truncated Elections of Different Sizes

Author(s): Piotr Faliszewski, Jitka Mertlová, Pierre Nunn, Stanisław Szufa, Tomasz Wąs
Published in: Proceedings of the AAAI Conference on Artificial Intelligence, Issue 39, 2025, Page(s) 13823-13830, ISSN 2374-3468
Publisher: Association for the Advancement of Artificial Intelligence (AAAI)
DOI: 10.1609/aaai.v39i13.33511

Robustness of approval-based multiwinner voting rules

Author(s): Piotr Faliszewski, Grzegorz Gawron, Bartosz Kusek
Published in: Review of Economic Design, 2025, ISSN 1434-4742
Publisher: Springer Verlag
DOI: 10.1007/s10058-025-00385-1

Drawing a map of elections

Author(s): Stanisław Szufa, Niclas Boehmer, Robert Bredereck, Piotr Faliszewski, Rolf Niedermeier, Piotr Skowron, Arkadii Slinko, Nimrod Talmon
Published in: Artificial Intelligence, Issue 343, 2025, Page(s) 104332, ISSN 0004-3702
Publisher: Elsevier BV
DOI: 10.1016/j.artint.2025.104332

Participatory budgeting with project groups

Author(s): Pallavi Jain, Krzysztof Sornat, Nimrod Talmon, Meirav Zehavi
Published in: Journal of Computer and System Sciences, Issue 156, 2026, Page(s) 103702, ISSN 0022-0000
Publisher: Academic Press
DOI: 10.1016/j.jcss.2025.103702

The Complexity of Subelection Isomorphism Problems

Author(s): Piotr Faliszewski, Krzysztof Sornat, Stanisław Szufa
Published in: Journal of Artificial Intelligence Research, Issue 80, 2024, Page(s) 1343-1371, ISSN 1076-9757
Publisher: Morgan Kaufmann Publishers, Inc.
DOI: 10.1613/jair.1.15550

How to tamper with a Parliament: Strategic campaigns in apportionment elections

Author(s): Robert Bredereck, Piotr Faliszewski, Michał Furdyna, Andrzej Kaczmarczyk, Joanna Kaczmarek, Martin Lackner, Christian Laußmann, Jörg Rothe, Tessa Seeger
Published in: Journal of Computer and System Sciences, Issue 155, 2026, Page(s) 103700, ISSN 0022-0000
Publisher: Academic Press
DOI: 10.1016/j.jcss.2025.103700

Maps of Tournaments: Distances, Experiments, and Data

Author(s): Filip Nikolow, Piotr Faliszewski, Stanisław Szufa
Published in: Frontiers in Artificial Intelligence and Applications, ECAI 2025, Issue 28th, 2025, Page(s) 675--682, ISBN 978-1-64368-631-8
Publisher: IOS Press
DOI: 10.3233/faia250866

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