Cotygodniowe seminarium badawcze (brak strony WWW)
2023-05-18, godz. 12:15, 4050
Natalia Kucharczuk (University of Warsaw)
Group Vitality Indices and the Shapley Value
We will start the presentation by showing a link between Vitality Indices and Shapley Value-based induced game-theoretic centralities. It is a foundation of our current research regarding extending vitality indices into groups. We propose novel definitions of Group Vitality Indices and Group Shapley...
2023-05-04, godz. 12:00, online
Grzegorz Pierczyński (University of Warsaw)
Market-Based Explanations of Collective Decisions
We consider approval-based committee elections, in which a size-k subset of available candidates must be selected given approval sets for each voter, indicating the candidates approved by the voter. A number of axioms capturing ideas of fairness and proportionality have been proposed for this framew...
2023-03-23, godz. 12:15, 4050
Jorge Salas (Pontificia Universidad Católica de Chile & University of Edinburgh)
How Do Centrality Measures Choose the Root of Trees?
Centrality measures are widely used to assign importance to graph-structured data. Recently, understanding the principles of such measures has attracted a lot of attention. Given that measures are diverse, this research has usually focused on classes of centrality measures. In this work, we provide ...
2023-03-16, godz. 12:15, 4050
Stanisław Szufa (AGH, Kraków)
Spoiler Susceptibility in Party Elections
An electoral spoiler is usually defined as a losing candidate whose removal would affect the outcome by changing the winner. So far spoiler effects have been analyzed primarily for single-winner electoral systems. We consider this subject in the context of party elections, where there is no longe...
2023-03-02, godz. 12:00, 4050
Sonja Kraiczy (University of Oxford)
The Mallows model is a popular distribution for ranked data. We empirically and theoretically analyze how the properties of rankings sampled from the Mallows model change when increasing the number of alternatives. We find that real-world data behaves differently than the Mallows model, yet is in li...
2023-02-02, godz. 12:00, zoom meeting
Oskar Skibski (University of Warsaw)
Closeness centrality via the Condorcet principle
We provide a characterization of closeness centrality in the class of distance-based centralities. To this end, we introduce a natural property, called majority comparison, that states that out of two adjacent nodes the one closer to more nodes is more central. We prove that any distance-based centr...
2023-01-12, godz. 12:15, 4050
Michał Pawłowski (University of Warsaw)
Optimizing ride-hailing fares using computational microeconomy tools
Pricing ride-hailing fares sparked a rich line of work in computer science due to its complexity and multidimensionality of aspects. We add to this line of research by considering the model presented by Hikima et al. (AAAI, 2021). For this model, the authors claimed a 3-approximation of the optimum ...
2023-01-05, godz. 12:00, spotkanie online
Piotr Faliszewski (AGH University in Kraków)
Map of Elections: Diversity, Polarization, and Agreement In Elections (+ some more)
In this talk I will present the idea of the map of (ordinal) elections and argue what it is good for. First, we will spend considerable amount of time on understanding diversity, polarization, and agreement within elections on the map. Then, we will look at other applications, such as using the map ...
2022-12-15, godz. 12:15, 4050
Stanisław Kaźmierowski (University of Warsaw)
Algorithm for solving the attack and interception game on networks
The paper "Attack and interception in networks" (F. Bloch, K. Chatterjee, B. Dutta, 2022), describes a game where a single attacker chooses a target and a path and each node chooses a level of protection. Main results proposed in this paper are the existence and uniqueness of NE of the pro...
2022-12-08, godz. 12:00, seminarium zdalne
Piotr Skowron (Uniwersytet Warszawski)
Proportionality in General Social Choice Models
We consider a model where a number of candidates need to be selected subject to certain feasibility constraints. The model generalises committee elections (where there is a single constraint on the number of candidates that need to be selected), various elections with diversity constraints, the mode...