# Dates from the work groups

### Johannes Rau (Bogotá): Tropical geometry and some applications

In my talk, I would like to introduce the main ideas of tropical geometry (from a geometric point of view) and then focus on some of the main applicactions, in particular, in the context of real algebraic geometry. In this context, tropical geometry can be understodd as a generalization of Viro's patchworking technique to construct real algebraic varieties with specific topological properties. Tropical methods can be used here to extend the technique to singular varieties and higher codimensions.

### Disputation Hannah Sjöberg

Thema der Dissertation: On Face Vector Sets and on Alcoved Polytopes Thema der Disputation: Geometry of Support Vector Machines

Location: WebEx Please ask a group member how to join.

### Disputation Anna Maria Hartkopf

Thema der Dissertation: Mathematical Science Communication a Study and a Case Study Thema der Disputation: Pentagonal Tilings of the Plane

Location: WebEx Please ask a group member how to join.

### Marwan Benyoussef: On the Hitchin morphism in positive characteristic

Location: The talk will be held via WebEx.

### ISMB 2020

Location: Montréal, Canada

### Trends in control theory at the interface of Systems & Synthetic Biology

Location: 2020 IFAC World Congress in Berlin, Estrel hotel and congress center

### Victor Martinez-Luaces: Visualizing roots of complex functions using sibling curves

Location: The talk will be held via WebEx. If you are interested in joining the meeting, please contact: beate.pierchalla@fu-berlin.de

### Serkan Emek: Iterated Robin problem for the higher order Poisson equation

Location: Die Veranstaltung wird via WebEx durchgeführt. Die Zugangsdaten werden noch bekannt gegeben.

### Habilitation Jean-Philippe Labbé

Location: WebEx Please ask a member of the work group for further information (e.g. Jonathan Kliem).

### Angel Luis Munoz Castaneda: Degenerations of semistable principal G-bundles on curves

Location: Arnimallee 3, SR 024, 14195 Berlin

### Workshop on Computational Models in Biology and Medicine

Location: Bonn, Germany

### Disputation Giulia Codenotti

Thema der Dissertation: Covering properties of lattice polytopes Thema der Disputation: Triangulations of products of simplices and the spread out simplices conjecture

Location: Arnimallee 3, SR 019

### Workshop "Mathematics for the Human Past"

Location: Zuse Institute Berlin

### Disputation Jorge Olarte

Location: Arnimallee 3, SR 119

### Einstein Workshop Polytopes and Algebraic Geometry 2019

This will be a three-day workshop with lectures, presentations and informal discussions on polytopes and their relations to algebraic geometry. It is funded by the Einstein Foundation Berlin , as part of Francisco Santos' Einstein Visiting Fellowship at FU Berlin for 2016-2020. It is one of the activities in the thematic Einstein semester Varieties Polyhedra and computations .

### INCOME2019

Location: Schankhalle, Berlin, Germany

### Colloquium in Honor of Rupert Klein’s 60th Birthday

Location: Zuse Institute Berlin (ZIB), Takustraße 7, 14195 Berlin

### The harmonic Green and Neumann functions of domains bounded by two intersecting circular arcs

Location: Arnimallee 3, SR 024, 14195 Berlin

### ICSB 2019

Location: Okinawa, Japan

### GAMM Workshop: "Computational and Mathematical Methods in Data Science"

Location: Freie Universität Berlin

### MATH+ Vortragsreihe: Dr. Nora Molkenthin

Dr. Nora Molkenthin, Max-Planck-Institut für Dynamik und Selbstorganisation, Göttingen Collective formation processes of dynamic networks Abstract : In systems with many units, the structure of their interaction often has significant impact on the behaviour of the system as a whole. Complex networks provide a unique tool for describing and investigating such systems, especially in the absence of symmetry. However, many of the available methods are more focused on specific static networks, while for many of the most interesting systems the interaction structure itself is subject to dynamical changes. In my work I have found many examples where the study of the dynamics giving rise to the interaction structures gave deep and novel insights into systems. In this talk I will focus on two examples from social networks and on-demand ride-sharing. The wide range of examples where this approach has been successful, leads to the question how these individual examples could be reflected in a wider theory for studying dynamical structure formation.

Location: Institut für Mathematik, Arnimallee 7, Raum E31, 14195 Berlin

### MATH+ Vortragsreihe: Dr. Nicolas Behr

Dr. Nicolas Behr, IRIF, Université Paris Diderot, France Rewriting theory for the social and life sciences Abstract : Somewhat surprisingly, despite the widespread use of models based upon transformations of graph-like objects in the applied sciences (chemical reaction systems, network models, random graph ensembles, tissue models, agent-based models, ...), the underlying theory and mathematics of so-called rewriting over adhesive categories appears to be relatively little known. In this talk, I will give a concise introduction to modern rewriting theory, and I will present two novel mathematical extensions of this framework: so-called rule algebras and tracelets for rewriting theories. Rule algebras permit to formulate a universal framework of continuous-time Markov chains arising from random transformation systems of graph-like structures, yielding a new tool-set for analyzing these systems, including in particular so-called combinatorial conversion (which permits to derive ODEs for the evolution of the statistical moments of pattern-counting observables). Tracelets on the other hand provide a mathematical formalism to extract high-level causal information from specifications of rewriting systems in terms of transformation rules and their base rates, sometimes referred to as "synthesis of explanations" (as opposed to the more standard approach of extracting statistical information from simulations). Originally developed as a precise mathematical implementation of the notion of pathways in biochemical reaction systems, this methodology aims to find high-level causal structures in sequences of rule compositions that permit to understand the dynamical behaviors of the typically highly complex random transformation system at hand. I will illustrate these novel concepts with application examples (such as a voter model of opinion formation) and provide some perspectives for high-performance software implementations of both the rule algebra and tracelet methodologies.

Location: Institut für Mathematik, Arnimallee 7, Raum E31, 14195 Berlin

### MATH+ Vortragsreihe: Dr. Sarah Wolf

Dr. Sarah Wolf, Global Climate Forum (GCF) Mathematik für Nachhaltigkeit - Entscheidungsunterstützung mit Hilfe agenten-basierter Modellierung Zusammenfassung: In meiner Forschung geht es um die Frage, wie Green Growth und eine nachhaltige Entwicklung erreicht werden können - ein Beispiel ist die derzeit viel diskutierte "Verkehrswende". Ökonomische Modelle, die in der Politikberatung vielfach eingesetzt werden, können oft per Konstruktion keinen Übergang aus einer gegebenen Ausgangslage hin zu einer strukturell veränderten Situation darstellen. Eine Alternative bieten agenten-basierte Modelle (ABM), die ein komplexes sozio-ökologisches Systems auf der Mikro-Ebene darstellen. Das Verhalten des Gesamtsystems betrachtet man dann mit Hilfe von Simulationen. Empirisch fundierte, hochaufgelöste ABM, die sich dazu eignen, mögliche Wege zu einer Verkehrswende (o.ä.) mit Stakeholdern zu diskutieren, bringen mehrere Herausforderungen mit sich: Die effiziente Parallelisierung solcher Simulationen ist weitgehend unerforscht, da die Interaktionsstrukturen der Agenten soziale Netzwerke mit geographischen Bedingungen mischen und daher von den (z.B. regelmäßigen Gitter-)Strukturen vieler HPC-Anwendungen abweichen. Die Analyse der Dynamik dieser Systeme wird dadurch erschwert, dass die Freiheit in der Wahl der Annahmen bei Definition und Implementierung eines Modells sehr groß ist. Mich interessieren grundlegende Modellstrukturen und Konzepte, mit denen man diese Herausforderungen angehen kann. Solche Modelle auf Basis von mathematischen Grundstrukturen sowohl einfacher implementieren als auch besser und schneller analysieren zu können, wäre nämlich hilfreich für eine wissenschaftliche Unterstützung von EntscheidungsträgerInnen. Diese können in "Decision Theatre"-Diskussionen mit dem Modell experimentieren und Folgen von verschiedenen Entscheidungen sofort eruieren. Umgekehrt können sie die weitere Modellentwicklung durch ihre Expertise aus der Praxis unterstützen.

Location: Institut für Mathematik, Arnimallee 6, Raum 031, 14195 Berlin

### MATH+ Vortragsreihe: Dr. Nataša Conrad

Dr. Nataša Conrad, Zuse Institute Berlin Dynamische Systeme und Datenwissenschaften in den Sozial- und Geisteswissenschaften Abstract: In this talk, I will present my main research results on the topic of modeling, simulation and analysis of complex social systems. In particular, I will focus on the study of processes of change on/of these systems and approaches I have developed for their studying. I will demonstrate the applicability of these methods on real-world examples from humanities and social sciences.

Location: Institut für Mathematik, Arnimallee 6, Raum 031, 14195 Berlin

### Workshop: Theory and applications of Boolean interaction networks

Location: Institute of Mathematics, Freie Universität Berlin, Arnimallee 6, SR 032, 14195 Berlin

### First Berlin - Leipzig Workshop on Fluctuating Hydrodynamics

Link to the workshop website

Location: Max Planck Institute for Mathematics in the Sciences and Institute of Mathematics, Freie Universität Berlin

### BMS Summer School 2019 on "Mathematics of Deep Learning"

Location: Zuse Institute Berlin

### SciCADE 2019

Location: Innsbruck, Austria

### ISMB/ECCB 2019

Location: Basel, Switzerland

### IBSB 2019

Location: Kyoto, Japan

### CECAM-Workshop: "Molecular and Chemical Kinetics - Sampling, Design and Machine Learning"

Location: Freie Universität Berlin

### Long Night of Science 2019

Location: Freie Universität Berlin

### Noether Konferenz 2019

Location: Arnimallee 3-5, Hörsaal 001, 14195 Berlin

### RECOMB 2019

Location: Washington, D.C., USA

### Honorary Colloquium on the occasion of Peter Deuflhard's 75 Birthday

Location: Zuse Institute Berlin (ZIB), Takustraße 7, 14195 Berlin

### HSB 2019

Location: Prague, Czech Republic

### "International Workshop on Recent Trends in Modelling, Simulation, Optimization and Data Analysis for Complex Systems", Champéry, Portes du Soleil, Switzerland

Location: Champéry, Portes du Soleil, Switzerland

### Tao Chen: Construction of Converging Goldberg-Coxeter Subdivisions of Discrete Surfaces

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### Oliver Labs: Cubic Surface Models and their Historical and Mathematical Background

In the 19 th century, cubic surfaces - defined by an implicit equation of degree three in three variables - were among the first interesting examples in the development of modern algebraic geometry. A well-known result by Arthur Cayley and George Salmon is that any smooth cubic contains exactly 27 straight lines. Other prominent facts are the classification of all cubic surfaces w.r.t. their singularities by Ludwig Schläfli, and Alfred Clebsch's birational map between the plane and such surfaces where six points play an essential role. The talk will present both the historical and the mathematical background of classical hand-crafted and also recent 3d-printed cubic surface models. Some of their fascinating features such as the movement of the straight lines as the surfaces vary may very well be visualized using interactive software. In 2011 and 2014, the speaker created two versions of a complete series of more than 45 types of 3d-printed cubic surface models. Copies of these are now part of several university collections such as those at Lisbon, Strasbourg, Dresden, and Mainz, as well as at the IHP at Paris. He will bring some examples of these sculptures with him in order to illustrate facts which may better be appreciated when seeing and touching a real object.

Location: HS 001/Arnimallee 3 (Tea/coffee will be served from 16:45 in room 006/A3.)

### Surface, Bulk, and Geometric Partial Differential Equations: Interfacial, stochastic, non-local and discrete structures

Workshop

Location: Mathematisches Forschungsinstitut Oberwolfach, Oberwolfach

### Prof. Phan Thanh An - The Law of Cosines for Computing Geometric Shortest Paths on a Convex Polytope in 3D

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### Guest Seminar WS1819

Location: A6/SR 007/008

### Guest Seminar WS1819

Location: A6/SR 007/008

### Einstein Workshop Geometric and Topological Combinatorics

Location: Freie Universität Berlin, Königin Luise Straße 24/26, 14195 Berlin

### ICSB 2018

Location: Lyon, France

### CSB Seminar Series

Location: Charité, Invalidenstraße 42, room 312a, 10115 Berlin

### Summer school "Modelling of Mass and Energy Transport"

Location: Institut für Mathematik, Arnimallee 6, Room 017, 14195 Berlin

### Dr. Kerem Halicioglu - The Earth’s gravity field through star images: Digital Zenith Camera Systems

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### Shira Faigenbaum - Repairing and Denoising Scattered Data for the Reconstruction of Manifolds Embedded in High Dimensions

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### ECCB 2018

Location: Athens, Greece

### DD XXV

Location: St. John's, Newfoundland, Canada

### IFIP TC 7 Conference on System Modelling and Optimization

Location: Essen, Germany

### Frank Neumann: Hochschild cohomology of dg-categories and spectral sequences

Location: SR 007/008, Arnimallee 6 (Tee/coffee will be served from 15:45 in room 006/A3)

### Vincent Trageser: On actions of non-reductive groups with a graded unipotent radical on affine varieties

Location: SR 140, A3 (Hinterhaus)

### ISMB 2018

Location: Chacago, United States

### SBMC 2018

Location: Bremen, Germany

### Yorck Sommerhäuser: Hopf Algebras - A short introduction

Location: HS 001/A3 (Tee/coffee will be served from 15:45 in room 006/A3).

### Bernd Kreussler: Means, Braids and Triangle Equations

Location: HS 001, A3 (Tea & coffee will be served from 4:45 pm in room 006, A3)

### Alejandra Rincón Hidalgo: Bridgeland stability conditions on the n-Kronecker quiver

Location: SR 140, A3 (HH)

### Encuentro Colombiano de Combinatoria ECCO 2018

Günter M. Ziegler (FU Berlin): „Polytopes — Extremal Examples and Combinatorial Parameters“

Location: Universidad del Norte, Barranquilla, Colombia

### Hanxing Lin: Introduction to Cauchy-Pompeiu type formulas on Riemann surfaces

Location: SR 140, A3 (HH)

### Heinrich Begehr: A hierarchy of complex partial differential operators II

Location: SR 140, A3 (HH)

### Heinrich Begehr: A hierarchy of complex partial differential operators

Location: SR 140, A3 (HH)

### IRI-Schering Colloquium "Organoids - Life in 3D"

Location: IRI Life Sciences, Philippstr. 13, Michaelis Building (No 18), Maud Menten Hall (3rd Floor), 10115 Berlin

### Prof. Ligang Liu: Progressive Parameterizations

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### aDVANCES IN SYSTEMS AND SYNTHETIC BIOLOGY 2018

Modelling Complex Biological Systems in the Context of Genomics Thematic Research School

Location: Évry, France

### Einstein Workshop Discrete Geometry and Topology

This will be a four day workshop with lectures, presentations and informal discussions on discrete geometry and topology, and related topics (combinatorial topology, computational geometry, polytope theory). It is primarily funded by the Einstein Foundation Berlin , as part of Francisco Santos' Einstein Visiting Fellowship at FU Berlin for 2016-2019. Additional funding is provided by the project Discretization in Geometry and Dynamics (SFB Transregio 109) and the Berlin Mathematical School . Read more.

Location: Freie Universität Berlin

### Defense Lauri Loiskekoski

Location: Seminar Room Arnimallee 2 14195 Berlin

### Ann-Sofie Fisker: Designing with Elastic Splines

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### Open-Acess-World-Café

Location: Freie Universität Berlin, Seminarzentrum, Raum: L 113 und L 116 (Erdgeschoss), Otto-von-Simson-Str. 26 (Silberlaube), 14195 Berlin

### CMSB 2017

Location: Darmstadt, Germany

### ENUMATH 2017

Location: Voss, Norway

### ÖMG-DMV-Jahrestagung 2017

Location: Paris-Lodron University of Salzburg

### Dr. Daisuke Sakurai: Topological analysis for multi-fields

Location: FU Berlin | Arnimallee 6 | Raum 108/109

### CP 2017

Location: Melbourne, Australia

### MSRI Program „Geometric and Topological Combinatorics“

Location: MSRI, Berkeley

### ICSB 2017

Location: Blacksburg, Virginia, USA

### IBSB 2017

Location: Berlin, Germany

### ISMB/ECCB 2017

Location: Prague, Czech Republic

### Workshop "Mathematics in Digital Humanities and Computational Social Science" to be held on June 30 and July 11, 2017

Location: Seminar Room (ZIB) Takustr. 7 14195 Berlin

### Reading Group on Real Algebraic Geometry

Location: Max Planck Institute for Mathematics in the Sciences Inselstraße 22 04103 Leipzig Germany

### IRI Summer School "Epigenetics meets mathematics"

Location: IRI Life Sciences, Humboldt-Universität zu Berlin, Germany

### Workshop "Mathematics in Digital Humanities and Computational Social Science" to be held on June 30 and July 11, 2017

Location: Seminar Room (ZIB) Takustr. 7 14195 Berlin

### Conference on Applied Topology

Location: Banach Center, Będlewo, Polen

### Long Night of the Sciences

Location: Berlin

### Discrete Geometry and Convexity - BÁRÁNY 70

Location: Renyi Institute of Mathematics, Budapest

### Defense Albert Haase

The square peg problem is at least 106 years old and still unsolved in full generality. It asks whether any simple closed curve in the plane inscribes a square. By “inscribes a square” we mean that the curve contains the four vertices of a square. The square itself may intersect both the bounded and unbounded components. Substantial progress on the problem has been made using methods from equivariant topology: Piecewise linear, analytic, convex, and locally monotone curves are all known to inscribe squares. We present a recent positive result by T. Tao that takes an entirely different, “analytical” approach involving areas defined by line integrals and Stokes’ theorem.

Location: Seminar Room