Workshop on Social Choice Theory

To mark the occasion of Sirin Botan's PhD defense, we are organising a one-day workshop in the centre of Amsterdam. There will be no registration fee, but we ask that you register here for the workshop so that we can keep track of the number of attendees.

Covid measures: In the Netherlands, masks currently are required on all public transport, and in public spaces such as supermarkets and shops. This also includes university buildings. Regulations require everyone moving around the building to wear a mask, and we encourage you to keep it on also when seated. Many places such as restaurants, cinemas, and museums require a coronavirus pass, though the university currently does not. We encourage everyone to take a self-test before coming to the workshop location. Social distancing (1.5-metre-rule) is required everywhere, except in places where access is limited to people with a coronavirus pass, such as a restaurant.

Attending the defense: Everyone is welcome to attend the PhD defense on Friday at 13:00. You can either follow the live stream or attend in person. The latter requires completing a registration form (not the one linked to above) in advance. Please contact us to get access (see bottom of this page).

When and Where?

The workshop will be held on Thursday, 25 November 2021 in the Belle van Zuylenzaal, in the building of the University Library at Singel 425.


13:45-14:00 welcome
14:00-14:45Marija Slavkovik (University of Bergen)
AI Ethics as a Social Choice Problem

AI should be researched, developed, deployed and used in light of human values. Who should decide what these values are? It has been argued that this decision should be a social choice problem. If we should just vote on it, should the majority decide? These are the questions explored in the talk.

14:45-15:30Piotr Faliszewski (AGH University of Science and Technology)
Map of Approval Elections

Map of elections is a tool for visualizing a set of elections coming either from real-life or from synthetic distributions. It shows similarity between elections and can help in visualizing their properties (such us the existence of a Condorcet winner or a score according to a given voting rule). However, so far, all the maps of elections made concerned ordinal elections. In this talk I will present preliminary results regarding making a map of approval elections. In particular, I will describe two natural metrics for measuring distance between elections and I will discuss a number of different synthetic distributions of elections, as well as the features of the elections they provide. For example, we will be wondering what is a natural counterpart of the Mallows distribution in the approval setting. I will also show preliminary results visualizing similarities between approval-based multiwinner voting rules.

This talk is based on joint (and ongoing) work with Lukasz Janeczko, Martin Lackner, Arkadii Slinko, Stanisław Szufa, and Nimrod Talmon.

15:30-16:00coffee break
16:00-16:45Simon Rey (University of Amsterdam)
 Non-Standard Models for Participatory Budgeting

In this talk I will discuss several recent papers on the topic of participatory budgeting. Participatory budgeting is usually studied as an extension of multi-winner voting, where selecting a candidate results in paying a cost, and where a budget limit constrains the cost of the selected candidates. Although highly relevant for the technical analysis, this approach does not fully capture participatory budgeting processes as they happen in real life. This talk aims at presenting other models for participatory budgeting that more closely resemble these real-life processes. We will discuss the idea of a two-stage model where agents first propose some projects and then vote over the shortlisted projects. We will also have a look at what changes when the process is repeated over several years. Finally, we will have a look at how to include additional constraints on top of the budget limit: quotas over categories of projects, dependencies between the projects, ...

16:45-17:30Felix Brandt (TU Munich)
 Donor Coordination

We study a mechanism design problem where a community of agents wishes to fund public projects via voluntary monetary contributions by the community members. An important application of this setting is donor coordination, which allows philanthropists to find an efficient and mutually agreeable distribution of their donations. We analyze various distribution rules (including the Nash product rule and the conditional utilitarian rule) and settle a long-standing open question of Bogomolnaia, Moulin, and Stong (2005) by showing that no strategyproof and efficient rule can guarantee that at least one approved project of each agent receives a positive amount of money. The proof reasons about 386 preference profiles and was obtained using a computer-aided method involving SAT solvers.

This is joint work with Florian Brandl, Dominik Peters, and Christian Stricker.


For any questions, please contact Sirin Botan.