Christoph Spiegel

deputy department head at ZIB since 2022
postdoctoral researcher at ZIB since August 2020

馃摤 Contact

office Room 3036 at ZIB
Room MA 607 at TUB
e-mail spiegel (at) zib.de
spiegel (at) campus.tu-berlin.de
homepage christophspiegel.berlin
languages German, English, and French

馃帗 Academic Background

Jun 2020 Ph.D. in Applied Mathematics at UPC
Mar 2015 M.Sc. in Mathematics at FUB
Dec 2012 B.Sc. in Mathematics at FUB

馃敩 Research

I like using computational tools for theoretical mathematics. Lately, I have utilized flag algebras, semidefinite programming, and discrete optimization to improve some long-standing bounds in extremal combinatorics. Currently, I am exploring the areas of proof verification and assistance.

Preprints

  1. Zimmer, M., Spiegel, C., and Pokutta, S. (2023). Sparse Model Soups: A Recipe for Improved Pruning Via Model Averaging. [arXiv]
    [BibTeX]
    @misc{zsp_modelsoup_23,
      archiveprefix = {arXiv},
      eprint = {2306.16788},
      primaryclass = {cs.LG},
      year = {2023},
      author = {Zimmer, Max and Spiegel, Christoph and Pokutta, Sebastian},
      title = {Sparse Model Soups: A Recipe for Improved Pruning Via Model Averaging}
    }
  2. Zimmer, M., Spiegel, C., and Pokutta, S. (2022). Compression-aware Training of Neural Networks Using Frank-Wolfe. [arXiv]
    [BibTeX]
    @misc{zsp_deepsparsefw_22,
      archiveprefix = {arXiv},
      eprint = {2205.11921},
      primaryclass = {cs.LG},
      year = {2022},
      author = {Zimmer, Max and Spiegel, Christoph and Pokutta, Sebastian},
      title = {Compression-aware Training of Neural Networks Using Frank-Wolfe}
    }
  3. Combettes, C., Spiegel, C., and Pokutta, S. (2020). Projection-free Adaptive Gradients for Large-scale Optimization. [arXiv] [summary] [code]
    [BibTeX]
    @misc{csp_adafw_20,
      archiveprefix = {arXiv},
      eprint = {2009.14114},
      primaryclass = {math.OC},
      year = {2020},
      author = {Combettes, Cyrille and Spiegel, Christoph and Pokutta, Sebastian},
      title = {Projection-free Adaptive Gradients for Large-scale Optimization},
      code = {https://github.com/ZIB-IOL/StochasticFrankWolfe},
      summary = {https://pokutta.com/blog/research/2020/10/21/adasfw.html}
    }
  4. Pokutta, S., Spiegel, C., and Zimmer, M. (2020). Deep Neural Network Training with Frank-Wolfe. [arXiv] [summary] [code]
    [BibTeX]
    @misc{zsp_deepfw_20,
      archiveprefix = {arXiv},
      eprint = {2010.07243},
      primaryclass = {cs.LG},
      year = {2020},
      author = {Pokutta, Sebastian and Spiegel, Christoph and Zimmer, Max},
      title = {Deep Neural Network Training with Frank-Wolfe},
      code = {https://github.com/ZIB-IOL/StochasticFrankWolfe},
      summary = {https://pokutta.com/blog/research/2020/11/11/NNFW.html}
    }
  5. Salia, N., Spiegel, C., Tompkins, C., and Zamora, O. (2019). Independent Chains in Acyclic Posets. [arXiv]
    [BibTeX]
    @misc{sstz_poset_19,
      archiveprefix = {arXiv},
      eprint = {1912.03288},
      primaryclass = {math.CO},
      year = {2019},
      author = {Salia, Nika and Spiegel, Christoph and Tompkins, Casey and Zamora, Oscar},
      title = {Independent Chains in Acyclic Posets}
    }

Conference proceedings

  1. Parczyk, O., Pokutta, S., Spiegel, C., and Szab贸, T. (2023). Fully Computer-assisted Proofs in Extremal Combinatorics. Proceedings of AAAI Conference on Artificial Intelligence. [arXiv] [slides] [code]
    [BibTeX]
    @inproceedings{ppss_ramsey_22,
      year = {2023},
      booktitle = {Proceedings of AAAI Conference on Artificial Intelligence},
      archiveprefix = {arXiv},
      eprint = {2206.04036},
      primaryclass = {math.CO},
      author = {Parczyk, Olaf and Pokutta, Sebastian and Spiegel, Christoph and Szab贸, Tibor},
      title = {Fully Computer-assisted Proofs in Extremal Combinatorics},
      code = {https://zenodo.org/record/6602512#.YyvFhi8Rr5g},
      slides = {https://pokutta.com/slides/20220705_DMD22_RamseyMultiplicity.pdf}
    }
  2. Ru茅 Perna, J. J., and Spiegel, C. (2023). The Rado Multiplicity Problem in Vector Spaces Over Finite Fields. Proceedings of European Conference on Combinatorics. [arXiv] [code]
    [BibTeX]
    @inproceedings{rs_radomult_23,
      year = {2023},
      booktitle = {Proceedings of European Conference on Combinatorics},
      archiveprefix = {arXiv},
      eprint = {2304.00400},
      primaryclass = {math.CO},
      author = {Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph},
      title = {The Rado Multiplicity Problem in Vector Spaces Over Finite Fields},
      code = {https://github.com/FordUniver/rs_radomult_23}
    }
  3. Zimmer, M., Spiegel, C., and Pokutta, S. (2023). How I Learned to Stop Worrying and Love Retraining. Proceedings of International Conference on Learning Representations. [arXiv] [code]
    [BibTeX]
    @inproceedings{zsp_retrain_21,
      year = {2023},
      booktitle = {Proceedings of International Conference on Learning Representations},
      archiveprefix = {arXiv},
      eprint = {2111.00843},
      primaryclass = {cs.LG},
      author = {Zimmer, Max and Spiegel, Christoph and Pokutta, Sebastian},
      title = {How I Learned to Stop Worrying and Love Retraining},
      code = {https://github.com/ZIB-IOL/BIMP}
    }
  4. Parczyk, O., Pokutta, S., Spiegel, C., and Szab贸, T. (2022). New Ramsey Multiplicity Bounds and Search Heuristics. Proceedings of Discrete Mathematics Days. [arXiv] [code]
    [BibTeX]
    @inproceedings{ppss_ramsey_22:1:,
      year = {2022},
      booktitle = {Proceedings of Discrete Mathematics Days},
      archiveprefix = {arXiv},
      eprint = {2206.04036},
      primaryclass = {math.CO},
      author = {Parczyk, Olaf and Pokutta, Sebastian and Spiegel, Christoph and Szab贸, Tibor},
      title = {New Ramsey Multiplicity Bounds and Search Heuristics},
      code = {https://zenodo.org/record/6602512#.YyvFhi8Rr5g}
    }
  5. Ru茅 Perna, J. J., and Spiegel, C. (2018). On a Problem of S谩rk枚zy and S贸s for Multivariate Linear Forms. Proceedings of Discrete Mathematics Days. [arXiv]
    [BibTeX]
    @inproceedings{rs_sarkozysos_18:1:,
      year = {2018},
      booktitle = {Proceedings of Discrete Mathematics Days},
      archiveprefix = {arXiv},
      eprint = {1802.07597},
      primaryclass = {math.CO},
      author = {Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph},
      title = {On a Problem of S谩rk枚zy and S贸s for Multivariate Linear Forms}
    }
  6. Kusch, C., Ru茅 Perna, J. J., Spiegel, C., and Szab贸, T. (2017). Random Strategies Are Nearly Optimal for Generalized Van Der Waerden Games. Proceedings of European Conference on Combinatorics. [URL] [arXiv]
    [BibTeX]
    @inproceedings{krss_randomstrategy_17:1:,
      year = {2017},
      booktitle = {Proceedings of European Conference on Combinatorics},
      url = {https://dmg.tuwien.ac.at/eurocomb2017/index.php/accepted-papers/},
      archiveprefix = {arXiv},
      eprint = {1711.07251},
      primaryclass = {math.CO},
      author = {Kusch, Christopher and Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph and Szab贸, Tibor},
      title = {Random Strategies Are Nearly Optimal for Generalized Van Der Waerden Games}
    }

Full articles

  1. Kam膷ev, N., and Spiegel, C. (2022). Another Note on Intervals in the Hales-Jewett Theorem. Electronic Journal of Combinatorics, 29(1). DOI: 10.37236/9400 [URL] [arXiv]
    [BibTeX]
    @article{ks_halesjewett_18,
      year = {2022},
      journal = {Electronic Journal of Combinatorics},
      volume = {29},
      number = {1},
      doi = {10.37236/9400},
      url = {https://combinatorics.org/ojs/index.php/eljc/article/view/v29i1p62},
      archiveprefix = {arXiv},
      eprint = {1811.04628},
      primaryclass = {math.CO},
      author = {Kam膷ev, Nina and Spiegel, Christoph},
      title = {Another Note on Intervals in the Hales-Jewett Theorem}
    }
  2. Cao-Labora, G., Ru茅 Perna, J. J., and Spiegel, C. (2021-10). An Erd艖s-Fuchs Theorem for Ordered Representation Functions. Ramanujan Journal, 56, 183鈥2091. DOI: 10.1007/s11139-020-00326-2 [URL] [arXiv]
    [BibTeX]
    @article{crs_erdosfuchs_19,
      year = {2021-10},
      journal = {Ramanujan Journal},
      volume = {56},
      pages = {183-2091},
      doi = {10.1007/s11139-020-00326-2},
      url = {https://link.springer.com/article/10.1007/s11139-020-00326-2},
      archiveprefix = {arXiv},
      eprint = {1911.12313},
      primaryclass = {math.NT},
      author = {Cao-Labora, Gonzalo and Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph},
      title = {An Erd艖s-Fuchs Theorem for Ordered Representation Functions}
    }
  3. Fabian, D., Ru茅 Perna, J. J., and Spiegel, C. (2021-08). On Strong Infinite Sidon and B鈧 Sets and Random Sets of Integers. Journal of Combinatorial Theory, Series A, 182. DOI: 10.1016/j.jcta.2021.105460 [URL] [arXiv]
    [BibTeX]
    @article{frs_sidon_19,
      year = {2021-08},
      journal = {Journal of Combinatorial Theory, Series A},
      volume = {182},
      doi = {10.1016/j.jcta.2021.105460},
      url = {https://sciencedirect.com/science/article/abs/pii/S0097316521000595},
      archiveprefix = {arXiv},
      eprint = {1911.13275},
      primaryclass = {math.CO},
      author = {Fabian, David and Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph},
      title = {On Strong Infinite Sidon and B鈧 Sets and Random Sets of Integers}
    }
  4. Corsten, J., Mond, A., Pokrovskiy, A., Spiegel, C., and Szab贸, T. (2020-10). On the Odd Cycle Game and Connected Rules. European Journal of Combinatorics, 89. DOI: 10.1016/j.ejc.2020.103140 [URL] [arXiv]
    [BibTeX]
    @article{cmpss_oddcyclegame_19,
      year = {2020-10},
      journal = {European Journal of Combinatorics},
      volume = {89},
      doi = {10.1016/j.ejc.2020.103140},
      url = {https://sciencedirect.com/science/article/abs/pii/S0195669820300615},
      archiveprefix = {arXiv},
      eprint = {1906.04024},
      primaryclass = {math.CO},
      author = {Corsten, Jan and Mond, Adva and Pokrovskiy, Alexey and Spiegel, Christoph and Szab贸, Tibor},
      title = {On the Odd Cycle Game and Connected Rules}
    }
  5. Candela, P., Serra, O., and Spiegel, C. (2020). A Step Beyond Fre沫man鈥檚 Theorem for Set Addition Modulo a Prime. Journal De Th茅orie Des Nombres De Bordeaux, 32(1), 275鈥289. DOI: 10.5802/jtnb.1122 [URL] [arXiv]
    [BibTeX]
    @article{css_freiman_18,
      year = {2020},
      journal = {Journal de Th茅orie des Nombres de Bordeaux},
      volume = {32},
      number = {1},
      pages = {275-289},
      doi = {10.5802/jtnb.1122},
      url = {https://jtnb.centre-mersenne.org/item/JTNB_2020__32_1_275_0/},
      archiveprefix = {arXiv},
      eprint = {1805.12374},
      primaryclass = {math.CO},
      author = {Candela, Pablo and Serra, Oriol and Spiegel, Christoph},
      title = {A Step Beyond Fre沫man's Theorem for Set Addition Modulo a Prime}
    }
  6. Ru茅 Perna, J. J., and Spiegel, C. (2020). On a Problem of S谩rk枚zy and S贸s for Multivariate Linear Forms. Revista Matem谩tica Iberoamericana, 36(7), 2107鈥2119. DOI: 10.4171/RMI/1193 [URL] [arXiv]
    [BibTeX]
    @article{rs_sarkozysos_18,
      year = {2020},
      journal = {Revista Matem谩tica Iberoamericana},
      volume = {36},
      number = {7},
      pages = {2107-2119},
      doi = {10.4171/RMI/1193},
      url = {https://ems.press/journals/rmi/articles/16818},
      archiveprefix = {arXiv},
      eprint = {1802.07597},
      primaryclass = {math.CO},
      author = {Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph},
      title = {On a Problem of S谩rk枚zy and S贸s for Multivariate Linear Forms}
    }
  7. Kusch, C., Ru茅 Perna, J. J., Spiegel, C., and Szab贸, T. (2019-09). On the Optimality of the Uniform Random Strategy. Random Structures & Algorithms, 55(2), 371鈥401. DOI: 10.1002/rsa.20829 [URL] [arXiv]
    [BibTeX]
    @article{krss_randomstrategy_17,
      year = {2019-09},
      journal = {Random Structures & Algorithms},
      volume = {55},
      number = {2},
      pages = {371-401},
      doi = {10.1002/rsa.20829},
      url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/rsa.20829},
      archiveprefix = {arXiv},
      eprint = {1711.07251},
      primaryclass = {math.CO},
      author = {Kusch, Christopher and Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph and Szab贸, Tibor},
      title = {On the Optimality of the Uniform Random Strategy}
    }
  8. Fre沫man, G. A., Serra, O., and Spiegel, C. (2019). Additive Volume of Sets Contained in Few Arithmetic Progressions. INTEGERS, 19. [URL] [arXiv]
    [BibTeX]
    @article{fss_additivevolume_18,
      year = {2019},
      journal = {INTEGERS},
      volume = {19},
      url = {https://math.colgate.edu/~integers/t34/t34.mail.html},
      archiveprefix = {arXiv},
      eprint = {1808.08455},
      primaryclass = {math.NT},
      author = {Fre沫man, Gregory A. and Serra, Oriol and Spiegel, Christoph},
      title = {Additive Volume of Sets Contained in Few Arithmetic Progressions}
    }
  9. Ru茅 Perna, J. J., Spiegel, C., and Zumalac谩rregui, A. (2018). Threshold Functions and Poisson Convergence for Systems of Equations in Random Sets. Mathematische Zeitschrift, 288, 333鈥360. DOI: 10.1007/s00209-017-1891-2 [URL] [arXiv]
    [BibTeX]
    @article{rsz_threshold_12,
      year = {2018},
      journal = {Mathematische Zeitschrift},
      month = feb,
      volume = {288},
      pages = {333-360},
      doi = {10.1007/s00209-017-1891-2},
      url = {https://link.springer.com/article/10.1007/s00209-017-1891-2},
      archiveprefix = {arXiv},
      eprint = {1212.5496},
      primaryclass = {math.CO},
      author = {Ru茅 Perna, Juan Jos茅 and Spiegel, Christoph and Zumalac谩rregui, Ana},
      title = {Threshold Functions and Poisson Convergence for Systems of Equations in Random Sets}
    }
  10. Spiegel, C. (2017). A Note on Sparse Supersaturation and Extremal Results for Linear Homogeneous Systems. Electronic Journal of Combinatorics, 24(3). DOI: 10.37236/6730 [URL] [arXiv]
    [BibTeX]
    @article{spiegel_supersaturation_17,
      year = {2017},
      journal = {Electronic Journal of Combinatorics},
      volume = {24},
      number = {3},
      doi = {10.37236/6730},
      url = {https://combinatorics.org/ojs/index.php/eljc/article/view/v24i3p38},
      archiveprefix = {arXiv},
      eprint = {1701.01631},
      primaryclass = {math.CO},
      author = {Spiegel, Christoph},
      title = {A Note on Sparse Supersaturation and Extremal Results for Linear Homogeneous Systems}
    }

馃挰 Talks and posters

Conference and workshop talks

Aug 2023
European Conference on Combinatorics, Prague [PDF]
Aug 2023
ICIAM 2023 Minisymposium: Advances in Optimization I, Tokyo [PDF]
Aug 2023
Conference on Discrete Optimization and Machine Learning, Tokyo [PDF]
Jun 2023
FoCM 2023 Workshop I.3: Graph Theory and Combinatorics, Paris [PDF]
May 2023
Combinatorial and Additive Number Theory Conference, New York [PDF]
View More / Less
Mar 2023
Workshop on Optimization and Machine Learning, Waischenfeld [PDF]
Feb 2023
AAAI Conference on Artificial Intelligence, Washington, DC [PDF]
Dec 2022
Workshop on Recent Advances in Optimization, Toronto [PDF]
Sep 2022
Workshop on Advances in Classical and Quantum Algorithms ..., Tokyo / Fukuoka [PDF]
Jul 2022
Discrete Mathematics Days, Santander [PDF]
Jun 2019
Postgraduate Combinatorial Conference, Oxford [PDF]
Jun 2019
GAPCOMB Workshop, Campelles
Jun 2018
Discrete Mathematics Days, Sevilla [PDF]
May 2018
Combinatorial and Additive Number Theory Conference, New York [PDF]
Sep 2017
The Music of Numbers, Madrid [PDF]
Jun 2017
Interactions with Combinatorics [PDF]
Mar 2017
FUB-TAU Workshop

Research seminar talks

Feb 2023
LIMDA Seminar, Barcelona [PDF]
Apr 2022
LIMDA Seminar, Barcelona
Nov 2019
Research Seminar Combinatorics, Berlin
Nov 2019
Combinatorics Research Seminar, Ilmenau
May 2019
PhD Seminar on Combinatorics, Games and Optimisation, London
View More / Less
May 2019
Combinatorial Theory Seminar, Oxford
Feb 2019
Extremal Set Theory Seminar, Budapest
Dec 2018
Research Seminar Combinatorics, Berlin
Mar 2018
GRAPHS at IMPA, Rio de Janeiro
Dec 2017
Research Seminar Combinatorics, Berlin
Oct 2017
LIMDA Seminar, Barcelona
May 2017
LIMDA Seminar, Barcelona
Mar 2016
LIMDA Seminar, Barcelona
Feb 2016
Research Seminar Combinatorics, Berlin
Jan 2016
Research Seminar Combinatorics, Berlin
Dec 2015
"What Is ...?" Seminar
Oct 2015
Research Seminar Combinatorics, Berlin

馃懆鈥嶐煆 Teaching

winter 2023
Lecturer for Einf眉hrung in die Lineare und Kombinatorische Optimierung (ADM I) at TUB
summer 2023
Lecturer for Analysis I und Lineare Algebra f眉r 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

馃摑 Organization

2023
Member of the organising committee of the MATH+ Thematic Einstein Semester in Berlin
Nov 2022
Assisted in the organisation of the Festkolloquium for Martin Aigner in Berlin
2022
Member of the organising committee of a Girls鈥 Day science outreach event in Berlin
Sep 2021
Member of the organising committee of the EUROCOMB conference in Barcelona
2021
Member of the organising committee of a Girls鈥 Day science outreach event in Berlin
Sep 2020
Organised exercise session on Robust Machine Learning for CO@Work summer school in Berlin
Oct 2017
Member of the organising committee of the BMS-BGSMath Junior Meeting in Barcelona
Jul 2016
Assisted in the organisation of the Symposium Diskrete Mathematik in Berlin
Jun 2016
Assisted in the organisation of the Discrete Mathematics Days in Barcelona