Monday, November 27, 2017
Technische Universität Berlin
Institut für Mathematik
Straße des 17. Juni 136
10623 Berlin
room MA 041
Lecture - 14:15
Abstract:
The goal of multiwinner elections is to select a group of k individuals
(the committee) based on the preferences of a number of agents (voters).
While the most prominent example of multiwinner elections comes from the
world of politics (parliamentary elections held in almost all modern
democracies), they are present nearly everywhere and include choosing
other representative bodies (e.g., working groups to deal with
particular issues), making various business decisions (e.g., choosing
products for an Internet store to put on its homepage, choosing movies
to put on a transatlantic flight), or shortlisting tasks (e.g.,
shortlisting applicants for a given academic position).
We will present a number of applications of multiwinner voting
(including the ones mentioned above), a number of multiwinner voting
rules, and a number of algorithms for computing them (most of the rules
are NP-hard to compute). Based on the axiomatic properties of the rules
and on simulation results, we will argue which rules are best-suited for
particular applications.
Colloquium - 16:00
Abstract:
We extend the principle of proportional representation to rankings:
given approval preferences, we aim to generate aggregate rankings so
that cohesive groups of voters are represented proportionally in each
initial segment of the ranking. Such rankings are desirable in
situations where initial segments of different lengths may be relevant,
e.g., in recommendation systems, for hiring decisions, or for the
presentation of competing proposals on a liquid democracy platform. We
define what it means for rankings to be proportional, provide bounds for
well-known aggregation rules, and experimentally evaluate the
performance of these rules.