Weekly research seminar

2022-10-13, 12:15, 4050

Michał Tomasz Godziszewski (University of Warsaw)

**Election control for VCR Euclidean preferences**Election control problems model situations where some entity (traditionally called the election chair) wants to ensure some agent's victory (the so-called, Constructive Control) or loss (the so-called Destructive Control) by either adding or deleting candidates or voters. Computational propertie...

2022-10-06, 12:00, online seminar

Marcin Dziubiński (University of Warsaw)

**Selecting a Winner with Impartial Referees**We consider a problem of mechanism design without money, where a planner selects a winner among a set of agents with binary types and receives outside signals (like the report of impartial referees). We show that there is a gap between the optimal Dominant Strategy Incentive Compatible (DSIC) mechan...

2022-07-06, 16:00, Spotkanie online

Stanisław Szufa (AGH University in Kraków)

**Numerical Experiments in Computational Social Choice**While many papers in computational social choice are theoretical, the number of experimental works is rapidly growing. During the tutorial, we will focus on experiments related to voting and participatory budgeting. We will discuss most popular statistical culture models (that serve for generatin...

2022-06-08, 16:00, seminarium zdalne

Marcin Waniek (New York University Abu Dhabi)

**Social diffusion sources can escape detection**Influencing (and being influenced by) others through social networks is fundamental to all human societies. Whether this happens through the diffusion of rumors, opinions, or viruses, identifying the diffusion source (i.e., the person that initiated it) is a problem that has attracted much research ...

2022-05-26, 10:15, 4050

Dorota Celińska-Kopczyńska (Instytut Informatyki, UW)

**Non-Euclidean Self-Organizing Maps**Self-Organizing Maps (SOMs, Kohonen networks) belong to neural network models of the unsupervised class. Most data analysts take it for granted to use some subregions of a flat space as their data model. However, assuming that the underlying geometry is non-Euclidean, we obtain a new degree of freed...

2022-05-12, 10:15, 4050

Michał Jaworski (Uniwersytet Warszawski)

**Phragmen 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, requires that larger subdivisions o...

2022-04-28, 10:15, 4050

Dominik Peters (Université Paris Dauphine-PSL)

**Fast Preference Elicitation and Fairness in Voting**Talk 1: Many decision making systems require users to indicate their preferences via a ranking. It is common to elicit such rankings through pairwise comparison queries. By using sorting algorithms, this can be achieved by asking at most O(m log m) adaptive comparison queries. However, in many ca...

2022-04-14, 10:15, 4050

Tomasz Wąs (Instytut Informatyki, UW)

**Understanding Distance Measures Among Elections**Motivated by putting empirical work based on (synthetic) election data on a more solid mathematical basis, we analyze six distances among elections, including, e.g., the challenging-to-compute but very precise swap distance and the distance used to form the so-called map of elections. Among the six,...

2022-03-31, 10:15, 4050

Marcin Dziubiński (Instytut Informatyki, UW)

**Discrete Two Player All-Pay Auction with Complete Information**We study discrete two player all-pay auction with complete information. We provide full characterization of mixed strategy Nash equilibria and show that they constitute a subset of Nash equilibria of discrete General Lotto game. We show that equilibria are not unique in general but they are intercha...

2022-03-17, 10:15, 4050

Adrian Górecki

We consider a setting where a group of individuals make a number of independent decisions. The decisions should proportionally represent the views of the voters. We formulate new criteria of proportionality and analyse two rules, Proportional Approval Voting and the Metod of Equal Shares, inspired b...