Johan Commelin

I am a PhD student under supervision of Ben Moonen. My main interest lies in algebraic geometry and algebraic number theory. I am funded by NWO project 613.001.207 (Arithmetic and motivic aspects of the Kuga–Satake construction).

Current research topics include: Hodge theory, Galois representations, motives, Mumford–Tate conjecture, periods.

Contact details

@: j.commelin (funny symbol) — PGP keys: [public] [private]
P: +31 (0)24 365 2865
A: HG 03.724
Heyendaalseweg 135
6525 AJ Nijmegen



Seminars that I organised (or co-organised).
Motivic Homotopy Theory Seminar (with Joost Nuiten)Spring 2015
Local Langlands Microsymposium (with Milan Lopuhaä)27 January 2015
Local Langlands Seminar (with Milan Lopuhaä)Autumn 2014
PhD ColloquiumSpring 2014 – Spring 2016
Basic Notions Reading GroupAutumn 2013


As teaching assistant in Nijmegen:

Rings and FieldsAutumn 2016
Algebraic Topology 2Spring 2016
Introduction to Algebraic CurvesAutumn 2015
Calculus 3&4Spring 2015
Abelian VarietiesAutumn 2014
Rings and FieldsSpring 2014

As teaching assistant in Leiden:

Algebra 1Spring 2013
Algebra 3Spring 2013
Seminar on Commutative AlgebraSpring 2012
Algebra 1Spring 2012
Projective GeometrySpring 2012
Analysis 3 (physics)Autumn 2011

Invited talks

28 Apr 2017
SGA seminar (Heidelberg) — The Mumford–Tate conjecture for products of K3 surfaces.
26 Apr 2017
SFB seminar (Mainz) — The Mumford–Tate conjecture for products of K3 surfaces.

Other talks

10 Apr 2017
Seminar on Perverse Sheaves — The decomposition theorem. Notes
15 Dec 2016
PhD colloquium — Chebotarev's density theorem.
7 Dec 2016
Crystalline seminar (Amsterdam, UvA) — Comparing infinitesimal cohomology with de Rham cohomology I. Notes
13 Oct 2016
PhD colloquium — Introduction to abelian varieties and the Mumford--Tate conjecture. Notes
19 Jan 2016
Faltings seminarp-divisible groups. Notes
30 Nov 2015
PhD colloquium — Periods (and why the fundamental theorem of calculus conjecturely is a fundamental theorem). Notes
26 Nov 2015
Diamant symposium — On the Mumford–Tate conjecture for the product of an abelian surface and a K3 surface. Slides
24 Nov 2015
Faltings seminar — Gabber's lemma. Notes
27 Oct 2015
GQT School — On the Mumford–Tate conjecture for surfaces with p_g = q = 2. Notes
27 May 2015
Mixed Homotopy Theory — Motivic cohomology. Notes
6 May 2015
Mixed Homotopy Theory — Smooth and étale morphisms. Notes
15 Apr 2015
Mixed Homotopy Theory — Intro to schemes and their basic properties. Notes
11 Dec 2014
Local Langlands seminar — Weil–Deligne representations. Notes
13 Nov 2014
Local Langlands seminar — Functional equation for GL2 and cuspidal local constants. Notes
23 Oct 2014
Abelian Varieties — Finite group schemes. Notes
3 Mar 2014
PhD colloquium (RU) — What is a motive? Notes
3 Dec 2013
Seminar on √Čtale Cohomology — Étale cohomology of fields. Notes
16 Jul 2013
Master's thesis defense — Algebraic cycles, Chow motives, and L-functions
18 Mar 2013
Topics in Algebraic Geometry — Good reduction. Notes
11 Feb 2013
Topics in Algebraic Geometry — Projective and noetherian schemes.
26 Apr 2012
Commutative Algebra seminar — Derivations and Differentials. Notes
26 Mar 2012
Topics in Algebraic Geometry — The structure of [N] II. Notes
19 Mar 2012
Topics in Algebraic Geometry — The structure of [N] I. Notes

Other writing

I wrote my master's thesis, titled Algebraic cycles, Chow motives, and L-functions, in the spring of 2013 under the supervision of Robin de Jong.

I wrote my bachelor's thesis, titled Tannaka Duality for Finite Groups, in the spring of 2011 under the supervision of Lenny Taelman.

Side projects