Weekly research seminar

2019-05-30, 10:15, 4050

Dorota Celińska-Kopczyńska (Wydział Nauk Ekonomicznych, UW)

**Applying non-Euclidean geometries to Social Network Analysis**Most data analysts take it for granted to use some subregions of a flat space as their data model, which means utilizing constructs that follow the principles of the Euclidean geometry. However, it is not the only option. We may use non-Euclidean geometries. The first of them, and probably the most ...

2019-04-25, 10:15, 4050

Marcin Waniek (New York University Abu Dhabi)

Multilayer networks allow for modeling complex relationships, where individuals are embedded in multiple social networks at the same time. Given the ubiquity of such relationships, these networks are increasingly gaining attention in the literature. We present the first analysis of the robustness o...

2019-04-11, 10:15, 4050

Michał Jaworski (Instytut Informatyki, UW)

**Multiwinner Elections - model with Issues**We study a model of Multiwinner Elections with Issues, in which we assume that an instance consists of a set of individuals (voters and candidates), desired committee size k and p Issues, which will be voted on by the winning committee. The goal is to select a winning committee such that decision ma...

2019-03-28, 10:15, 4050

Tomasz Wąs (Instytut Informatyki, UW)

**An Axiomatic Approach to the Manipulability of Centrality Measures**Centrality measures are among the most fundamental tools for social network analysis. Since network data is often incomplete, erroneous, or otherwise manipulated, increasing attention has recently been paid to studying the sensitivity of centrality measures to such distortions. However, thus far no ...

2019-03-07, 10:15, 4050

Piotr Skowron (Instytut Informatyki, UW)

**Proportionality Degree of Multiwinner Rules**We study multiwinner elections with approval-based preferences. An instance of a multiwinner election consists of a set of alternatives, a population of voters---each voter approves a subset of alternatives, and the desired committee size k; the goal is to select a committee (a subset) of k alternat...

2019-01-24, 10:15, 4050

Michał Godziszewski (Instytut Informatyki, UW)

**Judgement Aggregation and Multiwinner Elections**In most general terms, the theory of judgement aggregation (JA) investigates rules for making consistent collective judgements on a set of propositions on the basis of the group members' individual judgements on these propositions. A multiwinner election rule is a formal process for selecting a sub...

2018-12-06, 10:15, 4050

Grzegorz Pierczyński (Instytu)

**Approval-based elections and distortion of voting rules**We consider elections where both voters and candidates can be associated with points in a metric space and each voter prefers candidates that are closer to him/her to those that are further away. Such a metric space can be e.g. an issue space of their political views. We will measure the quality...

2018-11-22, 10:15, 4050

Oskar Skibski (Instytut Informatyki, UW)

**Attachment Centrality: Properties and Computation**Centrality indices aim to quantify the importance of nodes or edges in a network. Much interest has been recently raised by the body of work in which a node’s connectivity is understood less as its contribution to the quality or speed of communication in the network and more as its role in ena...

2018-11-08, 10:15, 4050

Tomasz Wąs (Instytut Informatyki UW)

We propose a new centrality measure, called the Random Walk Decay centrality. While most centralities in the literature are based on the notion of shortest paths, this new centrality measure stems from the random walk on the network. We provide an axiomatic characterization and show that the new cen...

2018-10-26, 12:15, 4050

Dominik Peters (Department of Computer Science, University of Oxford)

**Allocation of Indivisible Items with Connected Bundles**Suppose a collection of indivisible goods are arranged in a line, and we wish to allocate these items to agents so that each agent receives a connected bundle (an interval). This makes sense when the items have a spatial or temporal structure, for example when allocating time slots, and agents are i...