Organizers

dr Oskar Skibski
dr hab. Piotr Skowron

Information

Thursdays, 10:15 a.m. , room: 4050

Research fields

List of talks

Oct. 7, 2021, 10:15 a.m.
Grzegorz Pierczyński (Instytut Informatyki, UW)
Core-Stable Committees under Restricted Domains
We study the setting of committee elections, where a group of individuals needs to collectively select a given size subset of available objects. This model is relevant for a number of real-life scenarios including political …
June 17, 2021, 10:15 a.m.
Krzysztof Apt (Centrum Wiskunde & Informatica i Instytut Informatyki, UW)
Well-founded extensive games with perfect information
We consider extensive games with perfect information with well-founded game trees and study the problems of existence and of characterization of the sets of subgame perfect equilibria in these games. We also provide such characterizations …
April 29, 2021, 10:15 a.m.
Marcin Waniek (New York University Abu Dhabi)
Disinformation attacks on cities
Disinformation continues to raise concerns due to its increasing threat to society. Nevertheless, a disinformation-based attack on critical infrastructure has never been studied to date. In this line of work we consider two possible attack …
April 15, 2021, 10:15 a.m.
Tomasz Wąs (Instytut Informatyki, UW)
An Axiom System for Feedback Centralities
In recent years, the axiomatic approach to centrality measures has attracted attention in the literature. However, most papers propose a collection of axioms dedicated to one or two considered centrality measures. In result, it is …
March 18, 2021, 10:15 a.m.
Grzegorz Pierczyński (Instytut Informatyki, UW)
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 …
March 4, 2021, 10:15 a.m.
Dorota Celińska-Kopczyńska (Instytut Informatyki, UW)
Discrete Hyperbolic Random Graph Model
The hyperbolic random graph model (HRG) has proven useful in the analysis of scale-free networks, which are ubiquitous in many fields, from social network analysis to biology. However, working with this model is algorithmically and …
Jan. 28, 2021, 10:15 a.m.
Oskar Skibski (Instytut Informatyki, UW)
Signed Graph Games: Coalitional Games with Friends, Enemies and Allies
We extend the well-known model of graph-restricted games due to Myerson to signed graphs, where the link between any two players may be either positive or negative. Hence, in our model, it is possible to …
Dec. 17, 2020, 10:15 a.m.
Michał Godziszewski (Instytut Informatyki, UW)
An Analysis of Approval-Based Committee Rules for 2D-Euclidean Elections
We study approval-based committee elections for the case where the voters' preferences come from a 2D-Euclidean model. We consider two main issues: First, we ask for the complexity of computing election results. Second, we evaluate …
Dec. 3, 2020, 10:15 a.m.
Michał Lewandowski i Paweł Kalczyński (Zakład Analizy i Wspomagania Decyzji, SGH, College of Business and Economics, California State University – Fullerton)
Carpooling games
We define a new carpooling game (or more generally a task completion game) as an extension of the cost-sharing game and propose optimization algorithms to find stable allocations, i.e. match players to carpools and determine …
Nov. 19, 2020, 10:15 a.m.
Michał Jaworski (Instytut Informatyki, UW)
Phragmén Rules for Degressive and Regressive Proportionality
We study two concepts of proportionality in the model of approval-based committee elections. In degressive proportionality small minorities of voters are favored in comparison with the standard linear proportionality. Regressive proportionality, on the other hand, …
Nov. 12, 2020, 10:15 a.m.
Tomasz Wąs (Instytut Informatyki UW)
PageRank vs. Random Walk Decay Centrality
PageRank is one of the most important measures of node importance. However, multiple methods of manipulating PageRank have been identified. Recently, Random Walk Decay centrality was introduced as a harder to manipulate alternative to PageRank. …
Oct. 22, 2020, 10:15 a.m.
Grzegorz Pierczyński (Intytut Informatyki, UW)
Proportional Participatory Budgeting with Cardinal Utilities
We study voting rules for participatory budgeting, where a group of voters collectively decides which projects should be funded using a common budget. We allow the projects to have arbitrary costs, and the voters to …
Oct. 8, 2020, 10:15 a.m.
Marcin Dziubiński (Instytut Informatyki, UW)
Peer selection with external referees
The problem of peer selection is a problem facing a social planner who aims to choose a project of the highest quality from the set of projects submitted by a number of strategic agents. To …
March 5, 2020, 10:15 a.m.
Michał Godziszewski (Instytut Informatyki, UW)
Complexity of some multi-winner election rules over two-dimensional Euclidean single-peaked preferences
For a given election E=(V,C) the preferences \{\leq_i\}_{i \in V} of voters are single-peaked when, intuitively speaking, a single issue dominates their formation. This single dominating issue is normally represented by a one-dimensional real axis …
Jan. 30, 2020, 10:15 a.m.
Piotr Skowron (Instytut Informatyki, UW)
Proportionality and the Limits of Welfarism: Fairness with respect to power
We study two influential voting rules proposed in the 1890s by Phragmen and Thiele, which elect a committee or parliament of k candidates which proportionally represents the voters. Voters provide their preferences by approving an …