Johan Commelin

I am a postdoc in the group of Carel Faber. My main interest lies in algebraic geometry and algebraic number theory. From 2013 till 2017 I was a PhD student in Nijmegen, supervised by Ben Moonen.

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


Contact details

@: j.m.commelin (funny symbol) uu.nl — PGP keys: [public] [private]
P: +31 (0)30 253 4790
A: Budapestlaan 6
Room 506
3584 CD UTRECHT
The Netherlands

Publications/preprints


Invited talks

15 Nov 2017
Bielefeld — TBA.
05 Oct 2017
Strasbourg — On compatibility of the ℓ-adic realisations of abelian motives.
27 Jul 2017
AVGA conference (Poznań) — On compatibility of the ℓ-adic realisations of abelian motives.
30 Jun 2017
Freiburg — The Mumford–Tate conjecture for products of K3 surfaces.
14 Jun 2017
SCA seminar (Jussieu) — On compatibility of the ℓ-adic realisations of abelian motives.
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.

Seminars

Seminars that I organised (or co-organised).
SeminarSemester
Derived Algebraic Geometry Seminar (with Salvatore Floccari)Fall 2017
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

Teaching

As teaching assistant in Nijmegen:

CourseSemester
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:

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

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

My PhD thesis: On ℓ-adic compatibility for abelian motives & the Mumford–Tate conjecture for products of K3 surfaces [Erratum]. Completed in the summer of 2017 under the supervision of Ben Moonen.

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