Julian Ritter
Summary
I am a combinatorialist. I completed my Ph.D. at École polytechnique under the supervision of Vincent Pilaud in 2021. My research interests lie mainly in discrete geometry and polyhedral combinatorics. I am particularly interested in hyperplane arrangements, their posets of regions and polytopes associated to them.
I’m not an expery on the theory of numbers, but here are some special ones: My Erdős number is 4, via Martin Aigner, Günter M. Ziegler and Arnau Padrol, from all of whom I was fortunate to learn in person. Coincidentally, my Carlsen number is ♔#4 as well. My Bacon number, on the other hand, is still ∞.
Publications
2022 »Shard Polytopes«
International Mathematics Research Notices
Preprint on arXiv.org
joint work with Arnau Padrol and Vincent Pilaud
2021 »Removahedral Congruences Versus Permutree Congruences«
Electronic Journal of Combinatorics, vol. 28 (2021) no. 4
Preprint on arXiv.org
joint work with Doriann Albertin and Vincent Pilaud
2018 »Ranking the Teams in European Football Leagues with Agony«
Machine Learning and Data Mining for Sports Analytics, conference proceedings
joint work with Stefan Neumann and Kailash Budhathoki
Theses
2021 »Shard Polytopes and Quotientopes for Lattice Congruences of the Weak Order«
Ph.D. thesis
supervised by Vincent Pilaud
2016 »The Polytopes of Cardinality Homogeneous Set Systems«
Master’s thesis (PDF)
supervised by Günter M. Ziegler
2015 »Vehicle Routing Problems with Profits«
Bachelor’s thesis (PDF)
supervised by Ralf Borndörfer
Teaching
2021/22 Mathematik I
Lectures and exercise sessions
Technische Hochschule Brandenburg, Germany
2020/21 Mathematik I
Lectures and exercise sessions
Technische Hochschule Brandenburg, Germany
2019 INF411 – Les bases de la programmation et de l’algorithmique
Exercise sessions and tutorial sessions
École polytechnique, France
2019 INF361 – Introduction à l’informatique
Exercise sessions
École polytechnique, France
2018 INF411 – Les bases de la programmation et de l’algorithmique
Exercise sessions
École polytechnique, France
2018 INF311 – Introduction à l’informatique
Exercise sessions
École polytechnique, France
2018 CSE103 – Introduction to Algorithms
Tutorial sessions
École polytechnique, France
Talks (selection)
2022 »Shard Polytopes«
Summary, Slides
FPSAC 2021, Bar-Ilan University
2021 »Shard Polytopes and Quotientopes for Lattice Congruences of the Weak Order«
PhD thesis defense, online
2021 »Shard Polytopes«
Discrete Geometry Student Seminar, Freie Universität Berlin
2021 »Introduction aux arrangements, aux tessons et aux arcs«
Séminaire DGeCo, Sorbonne Université, Paris
2019 »Towards Type B Quotientopes«
AGDM Seminar, Technische Universität Wien
2019 »Some Hyperplane Arrangements, Some Posets and Some Polytopes«
Working seminar Discrete Geometry group, Freie Universität Berlin
2018 »The Poset of Regions of a Hyperplane Arrangement«
Combinatorics Working Seminar, Universität Wien
2017 »Le tirage au sort des huitièmes de finale de la ligue des champions«
Plateau Saclay Combinatorics Seminar, École polytechnique, France
2016 »Solving Periodic Event Scheduling Problems Efficiently by Reducing to SAT«
Summary, Slides
Student seminar »Periodic Timetabling and Passenger Routing«, Zuse-Institut Berlin
2016 »Improving Accessibility After a Disaster«
Summary
Student seminar »Network Interdiction Problems«, Freie Universität Berlin
Conferences attended
2019 »Einstein Workshop on Polytopes and Algebraic Geometry«
Freie Universität Berlin, Germany
2019 »Hyperplane Arrangements and Reflection Groups«
Leibniz Universität Hannover, Germany
2019 »Sage Days 100«
Universität Bonn, Germany
2019 »Summer School on Geometric and Algebraic Combinatorics«
Sorbonne Université, Paris, France
2019 »Free Computational Mathematics«
CIRM Luminy, France
2018 »Einstein Workshop on Algebraic Combinatorics«
Technische Universität Berlin, Germany
2018 »Einstein Workshop on Geometric and Topological Combinatorics«
Freie Universität Berlin, Germany
2018 Fall School »Order and Geometry«
Gutshof Sauen, Germany
2018 »Journées du groupe de travail CombAlg 2018«
Université de Paris 13, Villetaneuse, France
2018 »6th Encuentro Colombiano de Combinatoria«
Universidad del Norte, Barranquilla, Colombia
2018 Journée « Football et data »
Maison des X, Paris, France
2018 »Journées Nationales de l’Informatique Mathématique 2018«
École polytechnique, France
2018 »Cluster Algebras: Twenty Years On«
CIRM Luminy, France
2018 »Polytopes à Paris 2018«
Université Paris 6, France
2017 »Journées de Géométrie Algorithmique 2017«
Centre Paul Langevin, Aussois, France
2017 Journée « Flips »
Université Paris 13, France
2017 »Two Cluster Days«
Université Paris 6, France
2017 »Geometry and Combinatorics of Associativity«
Trinity College, Dublin, Ireland
Math Journalism (selection)
2017 »Gilt die Bauernregel des Fußballs noch?«
Zeit Online
How many points will be necessary to avoid relegation from the Bundesliga?
2016 »8 aus 47«
Zeit Online
How does the UEFA Champions League draw work?
2016 »Schluss mit Remis«
Zeit Online
Why are there so many draws in chess?
2016 »Nicht mal das kann die FIFA«
Zeit Online
What’s wrong with the FIFA World Ranking?
2015 »Die Tabelle lügt«
Fokus Fussball
Are there better ways to calculate a league table?
2015 »The Line-ups They Are a-Changin’«
Fokus Fussball
How much do line-ups change over the course of a season?
Contact
E-Mail firstname dot lastname at nailuj dot de
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