Author name cluster

Lena Schend

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

5 papers

2 author rows

JAIR Journal 2022 Journal Article

Altruistic Hedonic Games

Anna Maria Kerkmann
Nhan-Tam Nguyen
Anja Rey
Lisa Rey
Jörg Rothe
Lena Schend
Alessandra Wiechers

Hedonic games are coalition formation games in which players have preferences over the coalitions they can join. For a long time, all models of representing hedonic games were based upon selfish players only. Among the known ways of representing hedonic games compactly, we focus on friend-oriented hedonic games and propose a novel model for them that takes into account not only the players’ own preferences but also their friends’ preferences. Depending on the order in which players look at their own or their friends’ preferences, we distinguish three degrees of altruism: selfish-first, equal-treatment, and altruistic-treatment preferences. We study both the axiomatic properties of these games and the computational complexity of problems related to various common stability concepts.

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JAIR Journal 2020 Journal Article

Hedonic Games with Ordinal Preferences and Thresholds

Anna Maria Kerkmann
Jérôme Lang
Anja Rey
Jörg Rothe
Hilmar Schadrack
Lena Schend

We propose a new representation setting for hedonic games, where each agent partitions the set of other agents into friends, enemies, and neutral agents, with friends and enemies being ranked. Under the assumption that preferences are monotonic (respectively, antimonotonic) with respect to the addition of friends (respectively, enemies), we propose a bipolar extension of the responsive extension principle, and use this principle to derive the (partial) preferences of agents over coalitions. Then, for a number of solution concepts, we characterize partitions that necessarily or possibly satisfy them, and we study the related problems in terms of their complexity.

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AAMAS Conference 2016 Conference Paper

Altruistic Hedonic Games

Nhan-Tam Nguyen
Anja Rey
Lisa Rey
Jörg Rothe
Lena Schend

Hedonic games are coalition formation games in which players have preferences over the coalitions they can join. All models of representing hedonic games studied so far are based upon selfish players only. Among the known ways of representing hedonic games compactly, we focus on friend-oriented hedonic games and propose a novel model for them that takes into account not only a player’s own preferences but also her friends’ preferences under three degrees of altruism. We study both the axiomatic properties of these games and the computational complexity of problems related to various stability concepts.

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JAAMAS Journal 2014 Journal Article

Complexity of manipulation, bribery, and campaign management in Bucklin and fallback voting

Piotr Faliszewski
Yannick Reisch
Lena Schend

Abstract A central theme in computational social choice is to study the extent to which voting systems computationally resist manipulative attacks seeking to influence the outcome of elections, such as manipulation (i. e. , strategic voting), control, and bribery. Bucklin and fallback voting are among the voting systems with the broadest resistance (i. e. , NP-hardness) to control attacks. However, only little is known about their behavior regarding manipulation and bribery attacks. We comprehensively investigate the computational resistance of Bucklin and fallback voting for many of the common manipulation and bribery scenarios; we also complement our discussion by considering several campaign-management problems for these two voting rules.

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ECAI Conference 2012 Conference Paper

The Possible Winner Problem with Uncertain Weights

Dorothea Baumeister
Magnus Roos
Jörg Rothe
Lena Schend
Lirong Xia

The original possible winner problem is: Given an unweighted election with partial preferences and a distinguished candidate c, can the preferences be extended to total ones such that c wins? We introduce a novel variant of this problem in which not some of the voters' preferences are uncertain but some of their weights. Not much has been known previously about the weighted possible winner problem. We present a general framework to study this problem, both for integer and rational weights, with and without upper bounds on the total weight to be distributed, and with and without ranges to choose the weights from. We study the complexity of these problems for important voting systems such as scoring rules, Copeland, ranked pairs, plurality with runoff, and (simplified) Bucklin and fall-back voting.

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