Christopher Voll, PhD (cantab)

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Prof. Dr. Christopher Voll

Fakultät für Mathematik
Universität Bielefeld
Postfach 100131
D-33501 Bielefeld
Germany
Telephone: 0049-521-1065025
Telephone (secretary Ms Nopto): 0049-521-1065021
Email: surname at math dot uni minus bielefeld dot de

Elsevier boycott

I joined a number of researchers - more than 19.000 as of July 2021 - in boycotting Elsevier, the academic publisher; see The Cost of Knowledge for background.

CV

Click here for a 8-page CV (last updated in April 2021).

Research

My research interests are centred around asymptotic group theory, in particular arithmetic and analytic properties of zeta functions associated to infinite groups and rings. These are Dirichlet generating functions encoding arithmetic data about groups and rings, such as the numbers of finite index subobjects or finite-dimensional irreducible representations. The study of these zeta functions may be seen as a non-commutative analogue to the theory of the Dedekind zeta function of a number field, enumerating finite index ideals in the number field's ring of integers. This young subject area lies on the crossroads of infinite group and ring theory, algebraic geometry and combinatorics. I have written A newcomer's guide to zeta functions of groups and rings.

I welcome enquiries about possible PhD projects from suitably qualified candidates. I am also happy to consider sponsoring postdoc applications, e.g. under the Marie Curie Actions or the Alexander von Humboldt Foundation's schemes.

Book chapters

  1. Zeta functions of groups and rings - recent developments, in Groups St Andrews 2013 in St Andrews, editors C. M. Campbell, M. R. Quick, E.F. Robertson, C. M. Roney-Dougal, London Math. Soc. Lecture Note Ser. 422, 469--492, Cambridge Univ. Press, Cambridge, 2015, CUP
  2. A newcomer's guide to zeta functions of groups and rings, in B. Klopsch, N. Nikolov, C. Voll, Lectures on profinite topics in group theory, editor D. Segal, London Math. Soc. Stud. Texts 77, 99-144, Cambridge Univ. Press, Cambridge, 2011, CUP
  3. Zeta functions of groups and rings - functional equations and analytic uniformity, in Spectral Structures and Topological Methods in Mathematics, editors M. Baake, F. Götze, W. Hoffmann, EMS Series of Congress reports 13 (2019), 345--363, AMS bookstore.

Papers (published or accepted for publication)

  1. Generalized Igusa functions and ideal growth in nilpotent Lie rings, with A. Carnevale and M. M. Schein, arxiv, 34 pages, to appear in Algebra & Number Theory, (extended abstract (FPSAC 2020)).
  2. Flag Hilbert-Poincare series of hyperplane arrangements and their Igusa zeta functions, with J. Maglione, to appear in Israel J. Math., arxiv.
  3. Zeta functions of integral nilpotent quiver representations, with S. Lee, to appear in International Mathematics Research Notices (IMRN) (2021), rnab345, arxiv, pdf.
  4. Groups, graphs, and hypergraphs: average sizes of kernels of generic matrices with support constraints, with T. Rossmann, to appear in Memoirs of the Amer. Math. Soc., arxiv, 109 pages.
  5. Hessian matrices, automorphisms of p-groups, and torsion points of elliptic curves, with M. Stanojkovski, Math. Ann. 381 (2021), 593--629, pdf.
  6. Ideal zeta functions associated to a family of class-2-nilpotent Lie rings, The Quarterly Journal of Mathematics 71 (2020), 959--980, pdf.
  7. Enumerating graded ideals in graded rings associated to free nilpotent Lie rings, with S. Lee, Math. Z. 290 (2018), 1249--1276, pdf, arxiv
  8. Enumerating traceless matrices over compact discrete valuation rings, with A. Carnevale and S. Shechter, Israel J. Math. 227 (2018), 956--986, pdf, arxiv
  9. Orbit Dirichlet series and multiset permutations, with A. Carnevale, Monatsh. Math. 186 (2018), 215--233, pdf, arxiv
  10. Local functional equations for submodule zeta functions associated to nilpotent algebras of endomorphisms, Int. Math. Res. Not. IMRN (2017), pdf, arxiv
  11. Representation zeta functions of some nilpotent groups associated to prehomogenous vector spaces, with A. Stasinski, Forum Math. 29 (2017), 717--734, pdf, arxiv,
  12. Uniform analytic properties of representation zeta functions of finitely generated nilpotent groups, with Duong H. D., in Trans. Amer. Math. Soc. 369 (2017), 6327--6349, pdf, arxiv,
  13. Arithmetic groups, base change, and representation growth, with N. Avni, B. Klopsch and U. Onn, Geom. Func. Anal. (GAFA) 26 (2016), 67--135, pdf, arxiv
  14. Similarity classes of integral p-adic matrices and representation zeta functions of groups of type A_2, with N. Avni, B. Klopsch and U. Onn, Proc. Lond. Math. Soc. (3) 112 (2016), no. 2, 267 -- 350, pdf, arxiv.
  15. Enumerating classes and characters of p-groups, with E. A. O'Brien, Trans. Amer. Math. Soc. 367 (2015), 7775 -- 7796, pdf, arxiv
  16. Normal zeta functions of the Heisenberg groups over number rings I - the unramified case, with M. M. Schein, J. Lond. Math. Soc. 91 (2014), 19 -- 46, pdf, arxiv
  17. Normal zeta functions of the Heisenberg groups over number rings II - the non-split case, with M. M. Schein, Israel J. Math. 211 (2016), no. 1, 171 -- 195, pdf, arxiv
  18. Representation zeta functions of nilpotent groups and generating functions for Weyl groups of type B, with A. Stasinski, Amer. J. Math. 136 (2014), 501 -- 550, pdf, arxiv
  19. A New Statistic on the Hyperoctahedral Groups, with A. Stasinski, Electron. J. Combin. 20, issue 3 (2013), P50, pdf, arxiv
  20. Representation zeta functions of compact p-adic analytic groups and arithmetic groups, with N. Avni, B. Klopsch and U. Onn, Duke Math. J. 162 (2013), 111-197, pdf, arxiv
  21. Representation zeta functions of some compact p-adic analytic groups, with N. Avni, B. Klopsch and U. Onn, Cont. Math. 566 (2012), 295-330, arxiv
  22. Functional equations for zeta functions of groups and rings, Ann. Math. 172 (2010), 1181--1218, pdf, arxiv
  23. On representation zeta functions of groups and a conjecture of Larsen-Lubotzky, with N. Avni, B. Klopsch and U. Onn, C. R. Math. Acad. Sci. Paris, Ser. I 348 (2010), 363--367, pdf, arxiv
  24. Enumerating finite class-2-nilpotent groups on 2 generators, C. R. Math. Acad. Sci. Paris, Ser. I 347 (2009), 1347-1350, pdf, arxiv
  25. Zeta function of 3-dimensional p-adic Lie algebras, with B. Klopsch, Math. Z. 263, No. 1 (2009), 195--210, pdf, arxiv
  26. Igusa-type functions associated to finite formed spaces and their functional equations, with B. Klopsch, Trans. Amer. Math. Soc. 361 (2009), 4405--4436, pdf, arxiv
  27. Zeta functions of groups - singular pfaffians, in Essays in Geometric Group Theory, editor N. S. N. Sastry, Ramanujan Mathematical Society Lecture Notes Series, No. 9, 2009, arxiv
  28. Counting subgroups in a family of nilpotent semidirect products, Bull. London Math. Soc., No. 38 (2006), 743--752, pdf, arxiv
  29. Normal subgroup growth in free class-2-nilpotent groups, Math. Ann. 332, No. 1 (2005), 67--79, pdf, arxiv
  30. Functional equations for local normal zeta functions of nilpotent groups, with an appendix by A. Beauville, Geom. Func. Anal. (GAFA) 15 (2005), 274--295, pdf, arxiv
  31. Zeta functions of groups and enumeration in Bruhat-Tits buildings, Amer. J. Math. 126 (2004), 1005--1032, pdf, arxiv

Selected grants

Meetings (co-)organised

Postdocs

  1. Josh Maglione, 2018 - -present, funded partyly by DFG
  2. Viola Siconolfi, 2020 - 2021, now Postdoc at Pisa University
  3. Seungjai Lee, 2019 - 2021, now SNU Science Fellow at Seoul National University
  4. Mima Stanojkovski, 2017 - 2019, now MPI MIS, Leipzig (Nonlinear Algebra Group)
  5. Alastair Litterick, 2016 - 2019, Alexander von Humboldt-Fellow, now Lecturer at the University of Sussex, UK.
  6. Thomas Cauwbergs, 2015 - 2017, funded by DFG Sonderforschungsbereich 701
  7. Angela Carnevale, 2015 - 2018, partly funded by German-Israeli Foundation, now Lecturer at the National University of Ireland Galway
  8. Ann Kiefer, 2015 - 2017, FWO Postdoctoral Fellow, now postdoc at the Vrije Universiteit Brussel
  9. Matthew Levy, 2014 - 2016
  10. Tobias Roßmann, 2011 - 2016, funded by DFG Priority Programme "Algorithmic and Experimental Methods in Algebra, Geometry, and Number Theory" 1489, now Lecturer at the National University of Ireland Galway
  11. Duong Hoang Dung, 2013 - 2015, funded by DFG Sonderforschungsbereich 701, now Lecturer at the University of Wollongong, Australia
  12. Alexander Stasinski, 2009 - 2011, funded by EPSRC First Grant EP/F044194/1, now Professor at the University of Durham

PhD students

  1. Lars Bügemannskämper, 2021 - present
  2. Marlies Vantomme, 2019 - present
  3. Elena Tielker, 2018 - present, funded by DFG
  4. Paula Lins, 2015 - 2018 (degree awarded January 2019), now postdoc at KU Leuven Kulak, Belgium
  5. Michele Zordan, 2010 - 2015 (degree awarded April 2016), now Research Assistant at Imperial College, London
  6. Robert Snocken, 2008 - 2012 (degree awarded December 2014)

    7. Teaching (in German)

    Sommersemester 2021

    Wintersemester 2020/21

    Sommersemester 2020

    Wintersemester 2019/20

    Sommersemester 2019

    Forschungsfreisemester (sabbatical)

    Wintersemester 2018/19

    Sommersemester 2018

    Wintersemester 2017/18

    Sommersemester 2017

    Wintersemester 2016/17

    Sommersemester 2016

    Wintersemester 2015/16

    Sommersemester 2015

    Wintersemester 2014/15

    Sommersemester 2014

    Forschungsfreisemester (sabbatical)

    Wintersemester 2013/14

    Sommersemester 2013

    Wintersemester 2012/13

    Sommersemester 2012

    Wintersemester 2011/12

    BAföG

    Ich bin einer der Unterschriftsberechtigten der Fakultät für Mathematik für Leistungsbescheinigungen nach § 48 BAföG. Wenn Sie wünschen, dass ich eine solche Bescheinigung ausstelle, lesen Sie bitte diese Hinweise. Die fakultätsinternen Richtlinien für die Bewertung von Leistungen für diese Zwecke finden Sie hier.

    Last updated: 14 April 2022