Prof. Christian Stump

Research Team Leader
Algebraic Combinatorics

room: Building IB, Floor 3, Room 141
email: christian.stump(at)rub.de

assistants:
Annika Schulte (team assistant)
Peter Tissen (SPP2458 assistant)

office hours:
by appointment

I am professor for "Algebraic Combinatorics" and coordinator of the DFG priority program Combinatorial Synergies.

current teaching (winter term 2024/2025)

Previous Teaching since 2019

Summer term 2024

  • Research seminar "Kombinatorik" (vvz)
  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Lecture "Diskrete Mathematik für IT-Sicherheit" (ISITS, Bochum)

Winter term 2023/2024

  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Lecture "Geometrie" (vvz)
  • Research seminar "KI-Methoden in der Mathematik" (vvz)
  • Lecture "Diskrete Mathematik für IT-Sicherheit" (ISITS, Bochum)

Summer term 2023

  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Lecture "Diskrete Mathematik für IT-Sicherheit" (ISITS, Bochum)
  • Lecture "Algorithmische Mathematik für Informatiker" (vvz|moodle)

Winter term 2022/2023

  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Lecture "Elementargeometrie" (vvz)
  • Lecture "Diskrete Mathematik für IT-Sicherheit" (ISITS, Bochum)

Summer term 2022

  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Research seminar "Bochum-Frankfurt Kombinatorik-Seminar"
    with Prof. Sanyal (Frankfurt)
  • Lecture "Algorithmische Mathematik für Informatiker" (vvz)
  • Lecture "Diskrete Mathematik für IT-Sicherheit" (ISITS, Bochum)

Winter term 2021/2022

  • Seminar "Liegruppen und Liealgebren" (vvz)
  • Research seminar "Bochum-Frankfurt Kombinatorik-Seminar"
    with Prof. Sanyal (Frankfurt)
  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle

Summer term 2021

  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Seminar "Die symmetrische Gruppe - Darstellungstheorie und Kombinatorische Algorithmen" (vvz)
  • Lecture "Algebra II" (vvz)
  • Lecture "Algorithmische Mathematik für Informatiker" (vvz)

Winter term 2020/2021

  • Research seminar "Arrangements und Symmetrien" (vvz)
    with Prof. Röhrle
  • Introductory seminar "Praktische Anwendungen der Linearen Algebra" (vvz1|vvz2)
  • Lecture "Algebra I" (vvz)

Summer term 2020

  • Research seminar "Arrangements und Symmetrien"
    with Prof. Röhrle
  • Introductory seminar "Praktische Anwendungen der Linearen Algebra"
  • Lecture "Lineare Algebra II"

Winter term 2019/2020

  • Research seminar "Arrangements und Symmetrien"
    with Prof. Röhrle
  • Lecture "Lineare Algebra I"

Summer term 2019

  • Lecture "Vorkurs für künftige Studierende der Mathematik und Physik"

Winter term 2018/2019

  • Lecture "Computeralgebra in SageMath"

Previous teaching before 2019

Summer term 2017

  • Lecture "Einführung in die Darstellungstheorie" (OvGU Magdeburg)
  • Lecture "Mathematische Methoden II" (OvGU Magdeburg)
  • Introductory seminar "Anwendungen der Linearen Algebra" (OvGU Magdeburg)

Winter term 2016/2017

  • Research seminar "Diskrete Geometrie" (FU Berlin)

Summer term 2016

  • Introductory seminar "Anwendung der Linearen Algebra" (FU Berlin)
  • Research seminar "Diskrete Geometrie" (FU Berlin)

Winter term 2015/2016

  • Research seminar "Diskrete Geometrie" (FU Berlin)
  • Lecture "Lineare Algebra II" (FU Berlin)

Summer term 2014

  • Lecture "Elementargeometrie" (FU Berlin)

Winter term 2013/2014

  • Seminar "Liegruppen und Liealgebren" (FU Berlin)

Winter term 2011/2012

  • Block seminar "Sage und Cluster-Algebren" (Leibniz-Universität Hannover)

Winter term 2009 - summer term 2011

  • LaCIM Kombinatorik-Seminar (UQAM, Montréal, Canada)

Summer term 2009

  • Introductory seminar "Kombinatorik" (Universität Wien, Austria)

publications

You find my publications in the Zentralblatt Mathematik database and at MathSciNet (unfortunately not open access!).
Not necessarily final preprints of all my papers can be found on the arXiv Preprint server, you may as well visit my Google Scholar page.

2024

  • Chow and augmented Chow polynomials as evaluations of Poincaré-extended ab-indices
    Preprint; 10 pages, 2024 [arXiv].
  • The coarse flag Hilbert-Poincaré series of the braid arrangement
    Joint work with E. Hoster
    Preprint; 10 pages, 2024 [arXiv].
  • The Poincaré-extended ab-index.
    Joint work with G. Dorpalen-Barry and J. Maglione.
    J. Lond. Math. Soc. 111(1), 33 pages, 2024 [journal, arXiv].
  • Shi arrangements restricted to Weyl cones.
    Joint work with G. Dorpalen-Barry.
    Ann. Comb., 23 pages, 2024 [journal, arXiv].
  • A Hodge filtration of logarithmic vector fields for complex reflection groups.
    Joint work with T. Abe, G. Röhrle and M. Yoshinaga.
    J. Comb. Algebra 8(3/4), 251-278, 2024 [journal, arXiv].

2023

  • Central limit theorems for generalized descents and generalized inversions in finite root systems.
    Joint work with K. Meier.
    Electron. J. Probab. 28, 1-25, 2023 [journal, arXiv].
  • Bruhat intervals, subword complexes and brick polyhedra for finite Coxeter groups.
    Joint work with D. Jahn.
    Math. Z.304(2), 32 pp, 2023 [journal, arXiv].
    Extended abstract in Sém. Lothar. Combin. 86B FPSAC 2022 [journal].

2022

  • A face iterator for polyhedra and more general finite locally branched lattices.
    Joint work with J. Kliem.
    Discrete Comput. Geom. 67, 1147-1173, 2022 [journal, arXiv].
  • Standard complexes of matroids and lattice paths.
    Joint work with A. Engström and R. Sanyal.
    Vietnam J. Math., 17 pages, 2022 [journal, arXiv].

2021

  • Artificial intelligence aids intuition in mathematical discovery.
    Opinion piece, non-scientific contribution.
    Nature 600, 44-45, 2021 [journal].
  • Minkowski decompositions for generalized associahedra of acyclic type.
    Joint work with D. Jahn and R. Löwe.
    Alg. Comb. 4(5), 757-775, 2021 [journal, arXiv].
  • A combinatorial classification of 2-regular simple modules for Nakayama algebras.
    Joint work with R. Marczinzik and M. Rubey.
    J. Pure Appl. Algebra 225(3), 2021, 34p [journal, arXiv].

2020

  • Cataland: Why the Fuß?.
    Joint work with H. Thomas and N. Williams.
    To appear in Mem. AMS; preprint; 132 pages, 2020 [journal, arXiv].
  • Pure flag simplicial complexes and the Erdős-Ko-Rado-property.
    Joint work with J. Olarte, F. Santos and J. Spreer.
    J. Combin. Theory Ser. A 172, 2020, 29p [journal, arXiv].
  • Counting inversions and descents of random elements in finite Coxeter groups.
    Joint work with T. Kahle.
    Math. Comp. 89, 437-464, 2020 [journal, arXiv].

2019

  • FindStat - a database and search engine for combinatorial statistics and maps.
    Joint work with M. Rubey.
    Séminaire Lotharingien de Combinatoire, 82B.103, 8 pp., 2019 [journal].
  • Freeness of multi-reflection arrangements via primitive vector fields.
    Joint work with T. Hoge, T. Mano and G. Röhrle.
    Adv. Math. 350, 63-96, 2019 [journal, arXiv].

2018

  • Towards a uniform subword complex description of finite type cluster algebras.
    Joint work with S. Brodsky.
    Alg. Combin. 1(4), 545-572, 2018 [journal, arXiv].
  • Lipschitz polytopes of posets and permutation statistics.
    Joint work with R. Sanyal.
    J. Combin. Theory Ser. A 158, 605-620, 2018 [journal, arXiv].

2017

  • Double deficiencies of Dyck paths via the Billey-Jockusch-Stanley bijection.
    Joint work with M. Rubey.
    J. Integer Seq. 20(9), 9 pages, 2017 [journal, arXiv].
  • Noncrossing sets and a Graßmann associahedron.
    Joint work with F. Santos and V. Welker.
    Forum Math. Sigma 5, e5, 49 pages, 2017 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2014 [journal].
  • On non-conjugate Coxeter elements in well-generated reflection groups.
    Joint work with V. Reiner and V. Ripoll.
    Math. Z. 285(3), 2017, 1041-1062 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2015 [journal, slides].

2015

  • On root posets for noncrystallographic root systems.
    Joint work with M. Cuntz.
    Math. Comp. 84, 485-503, 2015 [journal, arXiv].
  • Brick polytopes of spherical subword complexes and generalized associahedra.
    Joint work with V. Pilaud.
    Adv. Math. 276, 1-61, 2015 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2012 [journal].
  • Vertex barycenter of generalized associahedra.
    Joint work with V. Pilaud.
    Proc. Amer. Math. Soc. 143, 2623-2636. 2015 [journal, arXiv].

2014

  • On a new collection of words in the Catalan family.
    J. Integer Seq. 17(7), 8 pages, 2014 [journal, arXiv].
  • Note on the transitive Hurwitz action on decompositions of Coxeter elements.
    Joint work with B. Baumeister, M. Dyer, and P. Wegener.
    Proc. Amer. Math. Soc. Ser. B 1, 149-154, 2014 [journal, arXiv].
  • Counting factorizations of Coxeter elements into products of reflections.
    Joint work with G. Chapuy.
    J. Lond. Math. Soc. 90(2), 919-939, 2014 [journal, arXiv].
  • Subword complexes, cluster complexes, and generalized multi-associahedra.
    Joint work with C. Ceballos and J.-P. Labbé.
    J. Algebraic Combin. 39(1), 17-51, 2014 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2012 [journal].

2013

  • FindStat - the combinatorial statistics database.
    Joint work with C. Berg.
    DMV Computeralgebra-Rundbrief 53, 2013.
    Updated version with C. Berg, V. Pons, T. Scrimshaw, and J. Striker, 2014 [arXiv].
  • More bijective Catalan combinatorics on permutations and signed permutations.
    J. Comb. 4(4), 419-447, 2013 [journal, arXiv].
  • EL-labelings and canonical spanning trees for subword complexes.
    Joint work with V. Pilaud.
    Fields Inst. Commun. Ser. Dis. Geom. Optim. 69, 213-248, 2013 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2013 [journal].
  • A uniform bijection between nonnesting and noncrossing partitions.
    Joint work with D. Armstrong and H. Thomas.
    Trans. Amer. Math. Soc. 365(8), 4121-4151, 2013 [journal, arXiv].

2012

  • Fillings of moon polyominoes, simplicial complexes, and Schubert polynomials.
    Joint work with L. Serrano.
    Electron. J. Combin. 19, 18 pages, 2012 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2011 [journal].

2011

  • A compendium on the cluster algebra and quiver package in Sage.
    Joint work with G. Musiker.
    Sém. Lothar. Combin. 67, 67 pages, 2011 [journal, arXiv].
  • A new perspective on k-triangulations.
    J. Combin. Theory Ser. A 118(6), 4121-4151, 2011 [journal, arXiv].
  • Counting the number of elements in the mutation classes of quivers of type Ã.
    Joint work with J. Bastian, T. Prellberg, and M. Rubey.
    Electron. J. Combin. 18(1), 23 pages, 2011 [journal, arXiv].

2010

  • Crossings and nestings in set partitions of classical types.
    Joint work with M. Rubey.
    Electron. J. Combin. 17, 19 pages, 2010 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2010 [journal].
  • q,t-Fuß-Catalan numbers for finite reflection groups.
    J. Algebraic Combin. 32(1), 67-97, 2010 [journal, arXiv].
    Extended abstract in Discrete Math. Theor. Comput. Sci. Proc. FPSAC 2008 [journal].

2009

  • On bijections between 231-avoiding permutations and Dyck paths.
    Sém. Lothar. Combin. 60, 13 pages, 2009 [journal, arXiv].

scientific software

I am the lead developer of the combinatorial statistics database www.FindStat.org.

  • FindStat is an online database of mathematical statistics on and maps between combinatorial objects. It provides tools for exploring relations between these statistics, aiding in research by allowing users to compute, compare, and visualize data.
  • The project was initiated in 2011 at the Université du Québec à Montréal, Canada, in collaboration with Chris Berg, and currently maintained in collaboration with Martin Rubey. It is indexed by ZentralBlatt zbMath.

I publish code contributions for the open source computer algebra system SageMath.org.

  • Many reviewed code contributions (250+ github issues) on many topics in algebra and combinatorics, such as a package on cluster algebras, reflection groups, cyclic sieving phenomena, and others.
  • Organization of coding prints: SageDays in 2015 (Hannover), 2016 (Berlin), 2018 (Berlin).

third-party funded research projects

All my DFG funded research projects are listed in the gepris.dfg.de database.

approved 2024:
AEI-DFG Research Project
PI of project component "Combinatorial Polytope Theory" (238.800€).
Joint with Raman Sanyal (Goethe-Universität Frankfurt) and Arnau Padrol, Vincent Pilaud (Universitat de Barcelona).

since 2024:
DFG Priority Program SPP2458 "Combinatorial Synergies"
Coordinator www.CombinatorialSynergies.de (1.163.450€)
PI of project "Machine learning combinatorial statistics and maps" (473.360€).

2021:
DFG State Major Instrumentation "Tier3 HPC Cluster Bochum"
PI in joint project with Alexander May from the Computer Science Faculty.

2017 - 2024:
DFG Heisenberg Program
PI of project "Noncrossing phenomena in Algebra and Geometry" (585.300€).

2013 - 2018:
DFG Research Grant
PI of project "Coxeter-Catalan Combinatoric I & II" (324.900€).

2013 - 2017:
DFG Priority Program SPP 1489 "Combinatorial and Geometric Structures for Reflection Groups and Groupoids"
PI of project "Algorithmic and Experimental Methods in Algebra, Geometry and Number Theory" (3.600€).
Joint with Michael Cuntz (Leibniz Universität Hannover).

2009 - 2011:
CRM-ISM fellowship, Université du Québec à Montréal, Canada (86.000€).

editorial activites

editorial board member since 2024:
Enumerative Combinatorics and Applications (ECA, electronic scientific journal)
Scope: Enumerative aspects of combinatorial structures and their connections to various areas of mathematics
Format: Peer reviewed (fully-refereed) and diamond open-access (free of charge to authors and reader).

editorial board member since 2020:
Combinatorial Theory (CT, electronic scientific journal)
Scope:
Discrete structures exhibiting a high degree of combinatorial complexity and representing substantial advances in the fields of Additive, Algebraic, Analytic, Enumerative, Extremal, Geometric, Probabilistic and Topological Combinatorics, as well as theoretical aspects of their applications to other areas of mathematics and the sciences.
Format: Peer reviewed (fully-refereed) and diamond open-access (free of charge to authors and reader).

executive board member since 2019:
Formal Power Series and Algebraic Combinatorics (FPSAC, conference series)
Scope: FPSAC is a series of annual international conferences series, first held in Lille (France) in 1988. It aims at linking leading researchers in combinatorics with mathematicians in allied fields drawn from pure mathematics, applied mathematics, theoretical computer science, physics, and biology. The principal topics include algebraic and enumerative combinatorics and their applications and relations with other areas of mathematics, physics, biology and computer science. This interdisciplinary nature is reinforced by the choice of plenary speakers. FPSAC emphasizes inclusiveness among participants and seeks to draw substantial participation from groups which have been traditionally underrepresented in the mathematical sciences, as well as to promote international participation.
Format: Annual one-week conference series with 250+ participants, several invited speakers, and  200+ submissions among which contributed talks and posters are selected by a yearly chaning program committee.

university administration

since 2023Fakultätsrat Mathematik (Listenplatz 1)
since 2021Kommission für Finanz- und Strukturfragen
since 2018Kommission für Datenfragen
2024Berufungskommission W1 Kombinatorik (Vorsitzender)
2023Berufungskommission W2 Geometrie und Darstellungstheorie
2019-2023Gemeinsamer Ausschuss des Optionalbereichs der Ruhr-Universität
2022Berufungskommission W2 Open Field
2021-2022Prüfungsausschuss Informatik
2020Berufungskommission W2 Numerik
2020-2021Konzeptionsgruppe Mathematikausbildung des neuen Studiengangs B.Sc. Informatik
2020Berufungskommission W3 Numerik
2019Berufungskommission W1 Logik und Verifikation

 

short cv

since 2018W2-Professor "Algebraic Combinatorics"Ruhr-Universität Bochum
2017-18Heisenberg fellowshipTechnische Universität Berlin
2017Deputy professorship "Algebra"Otto-von-Guericke-Universität Magdeburg
2015HabilitationFreie Universität Berlin
2013-17PI of DFG project "Coxeter-Catalan combinatorics"Freie Universität Berlin
2012-13Postdoctoral researcherLeibniz-Universität Hannover
2009-11Postdoctoral research fellowshipUniversité du Québec à Montréal, Canada
2008Doctoral DegreeUniversität Wien, Austria
2005DiplomaPhilipps-Universität Marburg
   

 

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