-
Article
Open AccessDynamic proportional rankings
Proportional ranking rules aggregate approval-style preferences of agents into a collective ranking such that groups of agents with similar preferences are adequately represented. Motivated by the application ...
-
Article
Open AccessApproval-based apportionment
In the apportionment problem, a fixed number of seats must be distributed among parties in proportion to the number of voters supporting each party. We study a generalization of this setting, in which voters c...
-
Article
Open AccessThe maximin support method: an extension of the D’Hondt method to approval-based multiwinner elections
We propose the maximin support method, a novel extension of the D’Hondt apportionment method to approval-based multiwinner elections. The maximin support method is a sequential procedure that aims to maximize ...
-
Article
Open AccessPhragmén’s voting methods and justified representation
In the late 19th century, Swedish mathematician Edvard Phragmén proposed a load-balancing approach for selecting committees based on approval ballots. We consider three committee voting rules resulting from th...
-
Article
Open AccessProportional representation in matching markets: selecting multiple matchings under dichotomous preferences
Given a set of agents with approval preferences over each other, we study the task of finding k matchings fairly representing everyone’s preferences. To formalize fairness, we apply the concept of proportional re...
-
Chapter
Strategic Voting and Strategic Candidacy
Models of strategic candidacy analyze the incentives of candidates to run in an election. Most work on this topic assumes that strategizing only takes place among candidates, whereas voters vote truthfully. In...
-
Article
The excess method: a multiwinner approval voting procedure to allocate wasted votes
In using approval voting to elect multiple winners to a committee or council, it is desirable that excess votes—approvals beyond those that a candidate, especially a shoo-in, needs to win a seat—not be wasted....
-
Chapter
Interactive Democracy: New Challenges for Social Choice Theory
Interactive Democracy (aka e-democracy or digital democracy) is an umbrella term that encompasses a variety of approaches to make collective decision making processes more engaging and responsive. A common goal o...
-
Article
Exact mean computation in dynamic time war** spaces
Averaging time series under dynamic time war** is an important tool for improving nearest-neighbor classifiers and formulating centroid-based clustering. The most promising approach poses time series averagi...
-
Article
Extending tournament solutions
An important subclass of social choice functions, so-called majoritarian (or C1) functions, only take into account the pairwise majority relation between alternatives. In the absence of majority ties—e.g., when t...
-
Article
On the structure of stable tournament solutions
A fundamental property of choice functions is stability, which, loosely speaking, prescribes that choice sets are invariant under adding and removing unchosen alternatives. We provide several structural insigh...
-
Article
Justified representation in approval-based committee voting
We consider approval-based committee voting, i.e. the setting where each voter approves a subset of candidates, and these votes are then used to select a fixed-size set of winners (committee). We propose a nat...
-
Article
Minimal retentive sets in tournaments
Tournament solutions, i.e., functions that associate with each complete and asymmetric relation on a set of alternatives a nonempty subset of the alternatives, play an important role in the mathematical social...
-
Chapter and Conference Paper
The Computational Complexity of Random Serial Dictatorship
In social choice settings with linear preferences, random dictatorship is known to be the only social decision scheme satisfying strategyproofness and ex post efficiency. When also allowing indifferences, random ...
-
Article
The Computational Complexity of Weak Saddles
We study the computational aspects of weak saddles, an ordinal set-valued solution concept proposed by Shapley. F. Brandt et al. recently gave a polynomial-time algorithm for computing weak saddles in a subcla...
-
Article
On the Complexity of Iterated Weak Dominance in Constant-Sum Games
In game theory, an action is said to be weakly dominated if there exists another action of the same player that, with respect to what the other players do, is never worse and sometimes strictly better. We inve...
-
Chapter and Conference Paper
The Computational Complexity of Weak Saddles
We continue the recently initiated study of the computational aspects of weak saddles, an ordinal set-valued solution concept proposed by Shapley. Brandt et al. gave a polynomial-time algorithm for computing w...
-
Chapter and Conference Paper
On the Complexity of Iterated Weak Dominance in Constant-Sum Games
In game theory, a player’s action is said to be weakly dominated if there exists another action that, with respect to what the other players do, is never worse and sometimes strictly better. We investigate the...
