Research

• Tariefdifferentiatie bij afval huishoudens effectief maar doel nog niet gehaald [Dutch, link]

with Roselinde Kessels and Levi Kroezen

De Rijksoverheid stelt steeds strengere doelen voor het scheiden van huishoudelijk afval, maar de afvalscheiding is de afgelopen jaren gestagneerd. Een verdere landelijke uitrol van tariefdifferentiatie en minder vaak inzamelen kan de afvalscheiding verder doen toenemen.

In het kort: 

• Tariefdifferentiatie en een lagere inzamelfrequentie zijn effectief, maar niet alle gemeenten lijken dit te willen.

• Afvalscheiding is lager onder ouderen, laagopgeleiden en niet-westerse migranten.

• Communicatie en ondersteuning op basis van demografie kan de effectiviteit van tariefdifferentiatie mogelijk vergroten.

• Envy-free Pricing of Seats in a Planetarium: Maximizing Revenue and Welfare with Geometric Valuation Structures

with J. Golak and A. Grigoriev

We study a geometric envy-free pricing problem with a single item demand. The aim of the seller is to maximize the revenue by assigning prices to points and by allocating customers to these points in an envy-free manner, i.e., every allocated customer receives a point of the highest possible utility and all non-allocated customers cannot afford any point. We also consider a discrete version where customers purchase the tiles of a regular tessellation of the plane. For the special case of continuous version of the problem, where all customers have the same preferred point, we introduce a dynamic programming algorithm solving the problem in polynomial time. For the discrete version of the problem, we extend the dynamic programming algorithm to the quasi-polynomial time approximation scheme.

• A multi-level model for value chains of smallholder farmer commodities 

with A. Grigoriev and in collaboration with the Fair and Smart Data research institute

We model the dynamics of and around the value chain for commodities like cocoa and coffee beans. A value chain is a set of activities performed to deliver a valuable product to the end customer. We use three different levels in our model, one for each type of decision maker: consumers, producers, and regulators. The consumer level tries to capture customers' decision-making when purchasing products in supermarkets or other retailers, while the regulator level models the market rules that are or can be in place. The value chain of the commodity from farmer to retailer is represented by the producer level. Since the policies currently in effect do not ensure that the premium we pay ends up at the farmers, our multi-level model aims at finding and testing adjusted regulations to ensure that the farmers ultimately earn a living income.

• Periodic Lock Scheduling Problem

with J. Golak, A. Grigoriev and T. van der Zanden

We consider a periodic lock scheduling problem. We assume that streams of vessels are arriving periodically and we aim to minimize the long-run average waiting time. We introduce closed-form formulae for the case of only 2 streams of arriving vessels. For the general case, we provide exact algorithms and an incremental polynomial-time approximation scheme. This creates tools for policy makers to further reduce CO2 emissions in the inland waterway transportation section.

• On the Diameter of Arrangements of Topological Disks

with A. Abiad, B. Aronov, M. de Berg, J. Golak and A. Grigoriev

Let B be a finite collection of n geometric (not necessarily convex) bodies in the plane. These objects naturally generalize the class of disks, ellipsoids, and even non-convex polygons. We consider geometric intersection multigraphs G_B where each body of the collection B is represented by a vertex, and two vertices of G_B are connected by k edges, with k being the number of the intersections between the corresponding bodies. In particular, for the case of two disks we prove that any two points in the plane can be connected by a Jordan curve that crosses the disk boundaries at most max{2, 2∆} times. For the general case of n disks, we prove that any two points in the plane can be connected by a Jordan curve that crosses the disk boundaries at most 2n(∆ + 1)^(n(n−1))min{n, ∆ + 1} times. As an important side result, we prove that the number of inclusion-maximal faces in A(D)—these are faces whose ply is more than the ply of their neighboring faces—is at most n(∆ + 1)^(n(n−1)).

• Research Fellowship, with Alex Grigoriev, Fair and Smart Data Institute (€15.000)

• Travel Grant, Maastricht University (€3.000)

• 2025 - Present: European Women in Mathematics – The Netherlands: Maastricht University representative

• 2024 - Present: Management Team member for the Data Analytics and Digitalization department

• 2024 - Present: Education Coordinator for the Data Analytics and Digitalization department

During PhD

• 2020 - 2024: Organization of PhD Brownbag seminar, an open seminar series at Maastricht University in which PhDs can practice their presentations and improve their presentation skills, while getting feedback on their research approach.

• 2021 - 2023: Data Analytics and Digitalization representative for the Maastricht University School of Business and Economics' PhD Committee

• 2022-2023: Reviewer for the School of Business and Economics' International Classroom Committee 2023

• Fair Trade Premiums: How Much Reaches the Farmers? [Blog]