I am an algebraic topologist with a special interest in the spectrum of topological modular forms TMF. I am also interested in several related
and unrelated questions in stable and unstable chromatic homotopy theory and (derived) algebraic geometry.
Currently I am thinking mostly about equivariant TMF, equivariant homotopy theory, algebraic K-theory and Brauer groups.
Preprints and Publications
Norms of Eilenberg-Mac Lane Spectra and Real Bordism, arXiv:2008.04963 (joint with XiaoLin Danny Shi and Mingcong Zeng)
On equivariant topological modular forms, arXiv:2004.10254 (joint with David Gepner)
Vanishing results for chromatic localizations of algebraic K-theory, arXiv:2001.10425 (joint with Markus Land and Georg Tamme)
Rings of modular forms and a splitting of TMF0(7) (joint with Viktoriya Ozornova), Selecta Mathematica, February 2020, 26:7 (arXiv)
A Whitehead theorem for periodic homotopy groups, arXiv:1811.04030 (joint with Tobias Barthel and Gijs Heuts, accepted in Israel Journal)
Topological modular forms with level structures: decompositions and duality, arXiv:1806.06709
Decomposition results for rings of modular forms, arXiv:1710.03461
Monadicity of the Bousfield-Kuhn functor (joint with Rosona Eldred, Gijs Heuts and Akhil Mathew), Proc. Amer. Math. Soc. 147 (2019), 1789-1796 (arXiv)
The Brauer group of the moduli stack of elliptic curves, arXiv:1608.00851 (joint with Ben Antieau, accepted in Algebra and Number Theory)
Gorenstein duality for Real spectra (joint with John Greenlees), Algebraic & Geometric Topology 17 (2017), 3547-3619 , (arXiv\>, Erratum to the published version)
Appendix B: 'Descent for higher real K-theories'
to 'Descent in algebraic K-theory and a conjecture of Ausoni-Rognes', arXiv:1606.03328
(joint with Niko Naumann and Justin Noel, 2016)
The C2-spectrum Tmf1(3) and its invertible modules (joint with Mike Hill), Algebraic & Geometric Topology 17 (2017) 1953-2011 (arXiv)
Fibration Categories are Fibrant Relative Categories, arXiv:1503.02036 , Algebraic & Geometric Topology 16 (2016), 3271-3300. (arXiv)
Fibrancy of Partial Model Categories (joint with Viktoriya Ozornova, 2015) Homology, Homotopy and Appl Volume 17.2 (2015), 53-80 (arXiv)
Affineness and Chromatic Homotopy Theory (joint with Akhil Mathew) J Topology (2015) 8 (2): 476-528 (arXiv, Erratum to the published version)
Vector Bundles on the Moduli Stack of Elliptic Curves, Journal of Algebra Volume 428 (2015), 425-456. (arXiv)
Hilbert Manifolds, Bulletin of the Manifold Atlas (2014, expository)
Spectral Sequences in String Topology, Algebraic & Geometric Topology 11 (2011), 2829-2860. (arXiv)
Lecture notes and expository writing
Academic Year 2020/21
Block 1, Bewijzen in de wiskunde
Block 2, Inleiding Topologie
Fall, Algebraic Topology I (jointly with Gijs Heuts)
Spring, Master seminar on spectral sequences and spectra (jointly with Gijs Heuts)
Academic Year 2019/20
Block 1, Elementaire Getaltheorie (all information on blackboard)
Fall, Mastermath Algebraic topology I
Fall, Orientation on Mathematical Research (WISM102)
Academic Year 2018/19
Block 3, Topologie en Meetkunde
Spring, Mastermath Algebraic Topology II (jointly with Gijs Heuts)
Spring, Master seminar on a rational homotopy theory (jointly with Gijs Heuts)
Academic Year 2017/18
Block 3, Topologie en Meetkunde
Spring, Master seminar seminar on topological K-theory (jointly with Gijs Heuts)
Previously, courses at the University of Virginia and the University of Bonn on linear algebra, multivariable calculus, algebra, homology theories and elliptic cohomology
Currently I supervise the PhD thesis of Jack Davies and master theses of Pascal Sitbon (Equivariant bordism) and Divya Ghanshani (Homology theories in cofibration categories)
In the past I have supervised the master theses of Simone Fabbrizzi (Brauer group of moduli stacks of elliptic curves), Joost van Geffen (The oriented cobordism ring), Jorge Becerra (K-theory with Reality), Jeroen van der Meer (KU-local stable homotopy theory) and Abe ten Voorde (Cyclic algebras over local fields arising from elliptic curves). Moreover I have supervised bachelor theses
on the topics of de Rham cohomology, applications of combinatorial topology to concurrent computation, homology with local coefficients, genus formulae of modular curves, framed bordism, principal bundles and elliptic curves. Generally I am happy to supervise bachelor theses in topology or on topics related to modular forms or elliptic curves.
If you are student interested in a thesis or reading project, please contact me!
Basic knowledge about topological spaces
Knowledge about basic constructions with vector spaces and abelian groups.
Some familiarity with categories and functors is also helpful. For those who haven't seen this before, the Intensive course on Categories and Modules at the start of the term is recommended.
Aim of the course
This course is an introduction to Algebraic Topology. Its main topic is the study of homology groups of topological spaces and their applications. These homology groups provide algebraic invariants of topological spaces which can be computed in many examples of interest. They are a bit like the fundamental group, only that they are abelian and also better adapted to study higher-dimensional phenomena.
In the first part of the course we will construct the singular homology groups of topological spaces and establish their basic properties, such as homotopy invariance and long exact sequences. In the second part of the course we will introduce CW-complexes. These provide a useful class of topological spaces with favorable properties, and we will explain how the homology of CW-complexes can be computed using cellular homology. We will also discuss some basic concepts from homotopy theory, in particular the generalization of the fundamental group to arbitrary homotopy groups.
Rules about homework/exam
There will be regular hand-in homework sets throughout the course and there will be a written exam at the end.
The score from the homework assignments will count as a bonus for the final examination: if the grade from the written exam is at least 5.0 and the average grade from the homework assignments is higher, then the written exam counts 75% and the homework assignments count 25%.
We will follow the lecture notes of Steffen Sagave
Additional literature includes
Bredon: Topology and Geometry
Hatcher: Algebraic Topology
For more information see the ELO page.