Christoph Spiegel

Researcher working on Combinatorics,
Optimization, and Learning

AIS2T @ Zuse Institute
Room 3036 • 14195 Berlin
spiegel@zib.de
Office hours

Wednesdays at ZIB
by e-mail appointment

about me

I am part of Sebastian Pokutta's IOL lab, deputy head of the AIS2T department at ZIB, and a member of MATH+. I also lead the seven person iol.COMP group and am co-PI of two MATH+ projects, each funding a PhD position. Click here if you are interested in joining.


I defended my PhD in additive and probabilistic combinatorics in 2020 at UPC Barcelona under Juanjo Rué and Oriol Serra and currently work on combinatorics, optimization, and learning. In particular, I like using optimization and AI tools for theoretical maths [1] [2] [3], flag algebras [4] [5] [6], and formal proof verification [7]. Click here for a complete list of my publications.


I teach most semesters at either TUB or FUB, usually on discrete mathematics. My next course is on formal proof verification with Lean. Click here for a complete list of courses.


I maintain both the Berlin Math Seminars page and the Formal Proofs from THE BOOK blog.

Publications

proceedings

  1. Kiem, A., Pokutta, S., and Spiegel, C.
    Categorification of Flag Algebras
    Proceedings of Discrete Mathematics Days, 2024. [URL]
  2. Kiem, A., Pokutta, S., and Spiegel, C.
    The 4-color Ramsey Multiplicity of Triangles
    Proceedings of Discrete Mathematics Days, 2024. [URL] [arXiv] [code]
  3. Mundinger, K., Pokutta, S., Spiegel, C., and Zimmer, M.
    Extending the Continuum of Six-Colorings
    Proceedings of Discrete Mathematics Days, 2024. [URL] [arXiv]
  4. Zimmer, M., Spiegel, C., and Pokutta, S.
    Sparse Model Soups: A Recipe for Improved Pruning Via Model Averaging
    Proceedings of International Conference on Learning Representations, 2024. [URL] [arXiv]
  5. Parczyk, O., Pokutta, S., Spiegel, C., and Szabó, T.
    Fully Computer-assisted Proofs in Extremal Combinatorics
    Proceedings of AAAI Conference on Artificial Intelligence, 2023. [DOI] [URL] [arXiv] [code]
  1. Kiem, A., Pokutta, S., and Spiegel, C.
    Categorification of Flag Algebras
    Proceedings of Discrete Mathematics Days, 2024. [URL]
  2. Kiem, A., Pokutta, S., and Spiegel, C.
    The 4-color Ramsey Multiplicity of Triangles
    Proceedings of Discrete Mathematics Days, 2024. [URL] [arXiv] [code]
  3. Mundinger, K., Pokutta, S., Spiegel, C., and Zimmer, M.
    Extending the Continuum of Six-Colorings
    Proceedings of Discrete Mathematics Days, 2024. [URL] [arXiv]
  4. Zimmer, M., Spiegel, C., and Pokutta, S.
    Sparse Model Soups: A Recipe for Improved Pruning Via Model Averaging
    Proceedings of International Conference on Learning Representations, 2024. [URL] [arXiv]
  5. Parczyk, O., Pokutta, S., Spiegel, C., and Szabó, T.
    Fully Computer-assisted Proofs in Extremal Combinatorics
    Proceedings of AAAI Conference on Artificial Intelligence, 2023. [DOI] [URL] [arXiv] [code]
  6. Rué, J. J., and Spiegel, C.
    The Rado Multiplicity Problem in Vector Spaces Over Finite Fields
    Proceedings of European Conference on Combinatorics, 2023. [DOI] [URL] [arXiv] [code]
  7. Zimmer, M., Spiegel, C., and Pokutta, S.
    How I Learned to Stop Worrying and Love Retraining
    Proceedings of International Conference on Learning Representations, 2023. [URL] [arXiv] [code]
  8. Parczyk, O., Pokutta, S., Spiegel, C., and Szabó, T.
    New Ramsey Multiplicity Bounds and Search Heuristics
    Proceedings of Discrete Mathematics Days, 2022. [arXiv] [code]
  9. Rué, J. J., and Spiegel, C.
    On a Problem of Sárközy and Sós for Multivariate Linear Forms
    Proceedings of Discrete Mathematics Days, 2018. [URL] [arXiv]
  10. Kusch, C., Rué, J. J., Spiegel, C., and Szabó, T.
    Random Strategies Are Nearly Optimal for Generalized Van Der Waerden Games
    Proceedings of European Conference on Combinatorics, 2017. [URL] [arXiv]

journal

  1. Mundinger, K., Pokutta, S., Spiegel, C., and Zimmer, M.
    Extending the Continuum of Six-Colorings
    Geombinatorics Quarterly, XXXIV, 2024. [URL] [arXiv]
  2. Parczyk, O., Pokutta, S., Spiegel, C., and Szabó, T.
    New Ramsey Multiplicity Bounds and Search Heuristics
    Foundations of Computational Mathematics, 2024. [DOI] [arXiv] [code]
  3. Kamčev, N., and Spiegel, C.
    Another Note on Intervals in the Hales-Jewett Theorem
    Electronic Journal of Combinatorics, 29(1), 2022. [DOI] [URL] [arXiv]
  4. Cao-Labora, G., Rué, J. J., and Spiegel, C.
    An Erdős-Fuchs Theorem for Ordered Representation Functions
    Ramanujan Journal, 56, 183–2091, 2021-10. [DOI] [URL] [arXiv]
  5. Fabian, D., Rué, J. J., and Spiegel, C.
    On Strong Infinite Sidon and Bₕ Sets and Random Sets of Integers
    Journal of Combinatorial Theory, Series A, 182, 2021-08. [DOI] [URL] [arXiv]
  1. Mundinger, K., Pokutta, S., Spiegel, C., and Zimmer, M.
    Extending the Continuum of Six-Colorings
    Geombinatorics Quarterly, XXXIV, 2024. [URL] [arXiv]
  2. Parczyk, O., Pokutta, S., Spiegel, C., and Szabó, T.
    New Ramsey Multiplicity Bounds and Search Heuristics
    Foundations of Computational Mathematics, 2024. [DOI] [arXiv] [code]
  3. Kamčev, N., and Spiegel, C.
    Another Note on Intervals in the Hales-Jewett Theorem
    Electronic Journal of Combinatorics, 29(1), 2022. [DOI] [URL] [arXiv]
  4. Cao-Labora, G., Rué, J. J., and Spiegel, C.
    An Erdős-Fuchs Theorem for Ordered Representation Functions
    Ramanujan Journal, 56, 183–2091, 2021-10. [DOI] [URL] [arXiv]
  5. Fabian, D., Rué, J. J., and Spiegel, C.
    On Strong Infinite Sidon and Bₕ Sets and Random Sets of Integers
    Journal of Combinatorial Theory, Series A, 182, 2021-08. [DOI] [URL] [arXiv]
  6. Corsten, J., Mond, A., Pokrovskiy, A., Spiegel, C., and Szabó, T.
    On the Odd Cycle Game and Connected Rules
    European Journal of Combinatorics, 89, 2020-10. [DOI] [URL] [arXiv]
  7. Candela, P., Serra, O., and Spiegel, C.
    A Step Beyond Freĭman’s Theorem for Set Addition Modulo a Prime
    Journal De Théorie Des Nombres De Bordeaux, 32(1), 275–289, 2020. [DOI] [URL] [arXiv]
  8. Rué, J. J., and Spiegel, C.
    On a Problem of Sárközy and Sós for Multivariate Linear Forms
    Revista Matemática Iberoamericana, 36(7), 2107–2119, 2020. [DOI] [URL] [arXiv]
  9. Kusch, C., Rué, J. J., Spiegel, C., and Szabó, T.
    On the Optimality of the Uniform Random Strategy
    Random Structures & Algorithms, 55(2), 371–401, 2019-09. [DOI] [URL] [arXiv]
  10. Freĭman, G. A., Serra, O., and Spiegel, C.
    Additive Volume of Sets Contained in Few Arithmetic Progressions
    INTEGERS, 19, 2019. [URL] [arXiv]
  11. Rué, J. J., Spiegel, C., and Zumalacárregui, A.
    Threshold Functions and Poisson Convergence for Systems of Equations in Random Sets
    Mathematische Zeitschrift, 288, 333–360, 2018. [DOI] [URL] [arXiv]
  12. Spiegel, C.
    A Note on Sparse Supersaturation and Extremal Results for Linear Homogeneous Systems
    Electronic Journal of Combinatorics, 24(3), 2017. [DOI] [URL] [arXiv]

preprint

  1. Zimmer, M., Andoni, M., Spiegel, C., and Pokutta, S.
    PERP: Rethinking the Prune-Retrain Paradigm in the Era of LLMs

    [arXiv] [code]
  2. Zimmer, M., Spiegel, C., and Pokutta, S.
    Compression-aware Training of Neural Networks Using Frank-Wolfe

    [arXiv]
  3. Combettes, C., Spiegel, C., and Pokutta, S.
    Projection-free Adaptive Gradients for Large-scale Optimization

    [arXiv] [summary] [code]
  4. Pokutta, S., Spiegel, C., and Zimmer, M.
    Deep Neural Network Training with Frank-Wolfe

    [arXiv] [summary] [code]
  5. Salia, N., Spiegel, C., Tompkins, C., and Zamora, O.
    Independent Chains in Acyclic Posets

    [arXiv]
Talks

Conference and Workshop Talks

October 202441st KolKom Conference, Heidelberg [PDF]

September 2024CO@Work, Berlin [PDF]

July 202413th DMD Conference, Alcalá de Henares [PDF]

October 2023   BMS RTA 8 - Practical Course, Berlin [PDF]

August 202312th EuroComb Conference, Prague [PDF]

October 202441st KolKom Conference, Heidelberg [PDF]

September 2024CO@Work, Berlin [PDF]

July 202413th DMD Conference, Alcalá de Henares [PDF]

October 2023   BMS RTA 8 - Practical Course, Berlin [PDF]

August 202312th EuroComb Conference, Prague [PDF]

August 2023ICIAM 2023 Minisymposium: Advances in Optimization I, Tokyo [PDF]

August 20235th DOxML Conference, Tokyo [PDF]

June 2023FoCM 2023 Workshop I.3 Workshop, Paris [PDF]

May 202315th CANT Conference, New York [PDF]

March 2023   Optimization and ML Workshop, Waischenfeld [PDF]

February 202337th AAAI Conference, Washington, DC [PDF]

January 2023combinatorial optimization workshop, Aussois [PDF]

December 2022Recent Advances in Optimization Workshop, Toronto [PDF]

September 20226th RIKEN-MODAL Workshop, Tokyo and Fukuoka [PDF]

July 202212th DMD Conference, Santander [PDF]

June 2019Postgraduate Combinatorial Conference, Oxford [PDF]

June 2019   GAPCOMB Workshop, Campelles [PDF]

June 201811th DMD Conference, Sevilla [PDF]

May 201810th CANT Conference, New York [PDF]

March 2018   GRAPHS at IMPA, Rio de Janeiro [PDF]

September 2017   The Music of Numbers Conference, Madrid [PDF]

June 2017Interactions with Combinatorics [PDF]

March 2017   FUB-TAU workshop [PDF]


Seminar Talks

February 2023LIMDA Seminar, Barcelona [PDF]

April 2022LIMDA Seminar, Barcelona [PDF]

November 2019Research Seminar Combinatorics, Berlin [PDF]

November 2019Research Seminar Large Networks and Random Graphs, Ilmenau [PDF]

May 2019Seminar on Combinatorics, Games and Optimisation, London [PDF]

February 2023LIMDA Seminar, Barcelona [PDF]

April 2022LIMDA Seminar, Barcelona [PDF]

November 2019Research Seminar Combinatorics, Berlin [PDF]

November 2019Research Seminar Large Networks and Random Graphs, Ilmenau [PDF]

May 2019Seminar on Combinatorics, Games and Optimisation, London [PDF]

May 2019Combinatorial Theory Seminar, Oxford [PDF]

February 2019   Extremal Set Theory Seminar, Budapest [PDF]

December 2018Research Seminar Combinatorics, Berlin [PDF]

December 2017Research Seminar Combinatorics, Berlin [PDF]

October 2017LIMDA Seminar, Barcelona [PDF]

May 2017LIMDA Seminar, Barcelona [PDF]

March 2016LIMDA Seminar, Barcelona [PDF]

February 2016Research Seminar Combinatorics, Berlin [PDF]

January 2016Research Seminar Combinatorics, Berlin [PDF]

December 2015"What is ...?" seminar [PDF]

October 2015Research Seminar Combinatorics, Berlin [PDF]

Teaching

Winter 2024   Lecturer for Formal Proof Verification at FUB

Summer 2024   Lecturer for Discrete Optimization (ADM II) at TUB

Winter 2023   Lecturer for Introduction to Linear and Combinatorial Optimization (ADM I) at TUB

Summer 2023   Lecturer for Analysis I und Lineare Algebra für Ingenieurwissenschaften at TUB

Autumn 2018   Assistant for Discrete Mathematics and Optimization at UPF

Autumn 2017   Assistant for Discrete Mathematics and Optimization at UPF

Winter 2013   Tutor for Analysis I (Lehramt) at FUB

Summer 2012   Tutor for Analysis II (Lehramt) at FUB

Summer 2011   Tutor for Analysis I (Lehramt) at FUB

Education

June 2020  Ph.D. in Applied Mathematics at Universitat Politècnica de Catalunya   [PDF]

March 2015  Master of Science at Freie Universität Berlin

September 2012  Bachelor of Science at Freie Universität Berlin

Juni 2009  Abitur at Canisius-Kolleg Berlin

Fun Stuff

You can find some of my photography on instagram. I also like designing the occasional conference poster: