talk · 2026-09
Trust, but Verify: Formal Proof Verification with Lean
Speinshart AI Workshop · Speinshart
Combinatorialist working on AI for Mathematical Discovery
Christoph Spiegel
Deputy head of AIS²T
at ZI
An extremal combinatorialist by training, I like to describe my approach as computational thinking: formalize problems to make them approachable through computational tools and AI.
Current & upcoming
course · winter 2026/27
Advanced Topics in Deep Learning: AI4Maths (MSc)
Guest Lecturer · TUB · English
course · winter 2026/27
Formal Proof Verification (BSc/MSc)
Lecturer · FUB/BMS · 5 ECTS · English
event · November 2026
KolKom 2026 – Kolloquium über Kombinatorik
I am organizing the 2026 iteration of the annual German combinatorics colloquium at TUB’s IMoS with support from ZIB and MATH+. Plenary talks will be given by Maria Axenovich, Matthew Kwan, Monique Laurent, and Mohit Singh. Submissions are welcome.
Recent preprints
P7
Limits of Combinatorial Patchworking
P6
Infinitely Many Counterexamples to a Conjecture of Lovász
P5
Forcing Graphs to be Forcing
Recent publications
J16
An Unsure Note on an Un-Schur Problem
J15
The Four-Color Ramsey Multiplicity of Triangles
J14
The Rado Multiplicity Problem in Vector Spaces over Finite Fields
C14
Fast Isotopy Computation for T-Curves
C13
Neural Sum-of-Squares: Certifying the Nonnegativity of Polynomials with Transformers
J13
Compression-aware Training of Neural Networks using Frank–Wolfe
Recent talks
Fast Isotopy Computation for T-Curves
8th DOxML Conference Tokyo
Coloring the Plane with Neural Networks
PACOH Workshop on AI for Combinatorics Jeju, South Korea
Coloring the Plane with Neural Networks
IBS ECOPRO Seminar Institute for Basic Science (IBS) Daejeon
An Unsure Talk on an Un-Schur Problem
Flags in the Mountains Workshop Bellvue
Formalizing Flag Algebras in Lean
Flags in the Mountains Workshop Bellvue
Event organization
November 2026
KolKom 2026 – Kolloquium über Kombinatorik
I am organizing the 2026 iteration of the annual German combinatorics colloquium at TUB’s IMoS with support from ZIB and MATH+. Plenary talks will be given by Maria Axenovich, Matthew Kwan, Monique Laurent, and Mohit Singh. Submissions are welcome.
August 2026
TIBOR – Colloquium on Extremal Combinatorics
I jointly organized this Colloquium on Turán Numbers, Intersections, Biased Games, Orientations, and Ramsey Graphs with Leticia Mattos. Plenary talks were given by Penny Haxell, Michael Krivelevich, Anita Liebenau, Mathias Schacht, and Gábor Tardos. As the choice of topics already suggests, we used this event to celebrate Tibor Szabó’s 60th birthday.
July 2026
Graph Theory and Combinatorics Workshop at FoCM
I jointly organized this workshop with Kurusch Ebrahimi-Fard and Claudia Malvenuto at FoCM 2026 in Vienna. Talks were given by Christian Krattenthaler, Stephanie van Willigenburg, Aida Abiad, Manuel Bodirsky, Loïc Foissy, Jan Hladký, Andrey Boris Khesin, Daniel Kráľ, Svante Linusson, Hong Liu, Arnau Padrol, Oleg Pikhurko, Pascal Schweitzer, Elizabeth Xiao, Alexandra Wesolek, and Hanmeng Harmony Zhan.
2024
ZIB40 Anniversary Events
I was a member of the organizing committee of the series of scientific and public events celebrating the 40th anniversary of the Zuse Institute Berlin.
Earlier events
February – September 2023
Thematic Einstein Semester 2023
I was part of the organizing committee for this MATH+ semester on mathematical optimization for machine learning. The program included workshops, a summer school, and a final conference.
November 2022
Festkolloquium for Martin Aigner at ZIB
I jointly organized this colloquium with Tibor Szabó to celebrate Martin Aigner’s 80th birthday at ZIB. Mathias Schacht, Emo Welzl, and Günter M. Ziegler gave lectures.
September 2021
EUROCOMB 2021 in Barcelona
I was part of the organizing committee for the European Conference on Combinatorics, which we held online.
October 2017
BMS–BGSMath Junior Meeting in Barcelona
I helped organize the first joint meeting of the Berlin and Barcelona graduate schools in mathematics, with keynote lectures and short talks by the participants.
Posters
Since my PhD years, I have liked to design the occasional conference or event poster. Click on each poster to get a full view or an overview of its variants.