New Humboldt postdocs have started at Mathematics Münster

In 2023, the Alexander von Humboldt Foundation accepted Prof. Dr. Franziska Jahnke, investigator at Mathematics Münster, as a Henriette Herz Scout. That means that she can recommend postdocs from abroad for a renowned Humboldt Research Fellowship which can be granted directly. Now she has taken this opportunity to bring Dr. Mariana Vicaria and Dr. Floris Vermeulen to Münster. "Both Floris and Mariana are amazing candidates, and being able to fast track them for scholarships gave me the edge to bring each of them to Münster", Franziska Jahnke says. They are an ideal addition to her research group. "Our strength as a team is that we all work in the model theory of valued fields, but we have very different backgrounds and hence can combine our different expertise to solve problems which none of us could solve alone."

Mariana Vicaria and Franziska Jahnke have embarked on a project on inp-minimal fields, aiming to show that all inp-minimal fields are bounded (i.e. they admit finitely many extensions of degree n for all n). They started working out the linearly ordered case first, as it seems more accessible.

Floris Vermeulen and Franziska Jahnke have started on a project around quantifier elimination in mixed characteristic deeply ramified fields with doctoral researcher Margarete Ketelsen, and on one around imperfect residue fields in motivic integration in mixed characteristic with Dr. Sylvy Anscombe (Université Paris Cité).

Interview with Mariana and Floris

Mariana Vicaria did her undergraduate and master studies at Universidad de los Andes, Colombia. She did her PhD at University of California, Berkeley, USA, under the supervision of Thomas Scanlon. After her graduation in 2022, she moved to UCLA (Los Angeles, CA) for her first postdoc (Hedrick Assistant Professor). In January 2025 she started her postdoc position in Münster.

Floris Vermeulen did his PhD with Raf Cluckers at KU Leuven, Belgium, and defended in May last year. Then he moved to Münster in September 2024 for his postdoc.

What were your reasons for choosing Münster for a research stay?

Mariana: Münster has a fantastic environment for model theory, the group here is very large and diverse. I work in model theory of valued fields, and I found the work of Franziska Jahnke on perfectoid fields remarkable and I found it very interesting to have the opportunity to collaborate with her. Also, Prof. Martin Hils is an expert on several topics of my interest, my previous work has been on elimination of imaginaries in valued fields building on previous work of Rideau-Kikuchi and Hils. On top of that, there are a number of other postdocs like Floris and PhD researchers like Marga Ketelsen who are doing very interesting work in model theory of valued fields. There is also a fantastic group of people working on geometric group theory lead by Prof. Katrin Tent which to my understanding will be unraveling one of the most interesting branches in model theory in the following years. So this is an easy question somehow, I came to Münster because the group of researchers here attract my interests, and I was certain that I could find new venues for my research and find nice collaborations. I should say and add, that the human environment and how welcoming the group is made some part also on my decision to come here. It was clear that my time in Münster will be more than enjoyable from the research and human side.  

Floris: Münster is really one of the best places for doing model theory. There is a large group of people working on valued fields here, and since I'm also working on this extensively, Münster was an obvious choice for me. I am really looking forward to learning more mathematics and to collaborate with new people. Moreover, the group here is very active and lively, with many activities both mathematical and non-mathematical going on all the time.

What are your expectations for your time in Münster?

Mariana: I hope to learn as much as possible while I am here, both from all the researchers around and from the very interesting lectures that are being held. I would like to find more collaborations with the group here, and we already started working in a project on inp-minimal fields with Franziska Jahnke.

Floris: I would like to broaden my perspective and learn a lot more about model theory, such as stability theory and Berkovich spaces. But more importantly is meeting new people and starting new collaborations. I already started a project about motivic integration over imperfect residue fields with Franziska Jahnke and Sylvy Anscombe, and a project about quantifier elimination in perfectoid fields with Franziska Jahnke and Margarete Ketelsen.

What are your first impressions of Münster and Mathematics Münster?

Mariana: Münster is great. I really like the city, how walkable it is and especially how welcoming the group has been. I was surprised to see the huge number of seminars and lectures that are being held, and also their quality. In none of my previous locations I have seen such a vivid research environment. I have attended a few lectures of Prof. Martin Hils, extremely enjoyable and carefully done. A few seminars from visitors on a diverse number of subjects were also very interesting. I was significantly impressed by the amount of people in the seminar room on model theory – it is even hard to find empty seats!

Floris: I really like how green and liveable the city of Münster is, and walking or running around the Aasee is always enjoyable. The mathematics group has been very welcoming, and I quickly felt at home in the group. There are many seminars and reading groups, which are ideal to learn new things. And of course the Common Room is a wonderful place to have a coffee and discuss mathematics.

Links:
Webpage Prof. Dr. Franziska Jahnke
Webpage Dr. Mariana Vicaria
Webpage Dr. Floris Vermeulen
Henriette Herz Scouting Programme (Humboldt Foundation)