Standard models of finite fields (with Hendrik Lenstra), chapter in: Handbook of Finite Fields

Index formulae for integral Galois modules [arxiv] (with Alex Bartel), to appear in the Journal of the LMS

Inverse Problems for deformation rings [arxiv] (with Frauke Bleher, Ted Chinburg), to appear in TAMS.

Isospectral surfaces with distinct covering spectra via Cayley Graphs [arxiv] (with Ruth Gornet, Craig J. Sutton) Geometriae Dedicata , Volume 158, Issue 1 (2012), Page 343-352

The valuation criterion for normal basis generators (with Mathieu Florence, Lara Thomas), Bull. London Math. Soc (2012) 44 (4): 729-737

Lambda actions of rings of integers [arxiv] (with Jim Borger), 2011

Sunada's method and the covering spectrum [arXiv],
J. Differential Geom. 86 (2010), no. 3, 501-537

More ...


Informal notes

2008-09-26 Standard models of finite fields: the definition [PDF]

2007-06-15: On the characteristic polynomial of the sum of two endomorphisms [PDF]

2007-06-10: Wreath products and Galois groups [PDF]

2005: Multilinear algebra [PDF] (notes of Arjen Stolk)

2005: Different and discriminant [PDF] (notes of Arjen Stolk)

2003: An algebraic proof of Brauer's class number relations [PS]

2000: Incomplete completions of local rings [PDF] (with H.W. Lenstra)


PhD Students

- Pavel Solomatin (expected 2017)
- Qijun Yan (expected 2016)
- Krzysztof Dorobisz (2015)
Willem Jan Palenstijn (2014)
- Andrea Siviero (2013)
- Bas Jansen (2012)
- Lara Thomas (2005)
- Mascha Honsbeek (2005)
- Richard Groenewegen (2003)

Masters Students

Stefano Marseglia (2013)
Marta Lucchini (2012)
Johannes van der Horst (2010)
Marco Perone (2007)
Hendrik Verhoek (2006)
Jos Brakenhof (2005)
Willem Jan Palenstijn (2004)
Ana Lukic (2003)
Bas Jansen (2002)
Lara Thomas (2002)


Research program number theory and algebra at the Universiteit Leiden.

2006-2010: Marie Curie Research Training Network Galois theory and explicit methods

2004-2008: NWO Open Competitie Radicals in arithmetic

1998-2002: KNAW Akademieonderzoeker Class numbers, L-series and permutation modules


July 2010: Sage Days Leiden

October 2009, Leiden: Frobenius lifts

September 2009, Warwick: GTEM 3

June 2008, Amsterdam: Minisymposium Galois theory and explicit methods 5ECM

June 2006: Rings of Low Rank