# Summer schools, block courses, workshops

### 5th Graduate Student Meeting in Applied Algebra and Combinatorics

The 5th Graduate Student Meeting in Applied Algebra and Combinatorics will take place in Berlin from April 10-12, 2024.

### Ph.D. defense of Vuong Bui: Growth of polyominoes and of bilinear maps

The Ph.D. defense starts with a 25' lecture about Growth of polyominoes (see below for the abstract), which is followed by a discussion and a short presentation of the Ph.D. thesis with the title: Growth of bilinear maps Abstract of the first talk: Growth of polyominoes A polyomino is an edge-connected set of cells in the square lattice. Although the notion is simple and natural, many problems related to polyominoes are open, namely computing efficiently the number of polyominoes A(n) with n cells and estimating its exponential growth constant λ = lim {n→∞} A(n)^ (1/n) , which is known as Klarner's constant. The best algorithm for the former problem still suffers the exponential time complexity, whose base can be decreased usually by using more space. It follows that the natural way to bound λ from below by A(n)^ (1/n) asks for a lot of computation. The best approach for a bound so far is by considering twisted cylinders, a model that is similar to polyominoes but a bit simpler to compute. This allows the lower bound to just exceed 4 by Barequet, Rote, and Shalah in 2016, which is close to the believed value λ ≈ 4.06. The known upper bounds are however not so good: the bound 4.65 has existed since 1973 by Klarner and Rivest, and only very recently got improved to 4.53 in 2022 by Barequet and Shalah, which actually asks for a good deal of computation. Related aspects and new approaches will be also discussed.

Location: Seminarraum 053 Institut für Informatik Takustraße 9 Freie Universität Berlin

### Vernetzungstreffen der deutschen Informatik-Graduiertenkollegs in Dagstuhl, 12.-15. Juni 2022

Das Vernetzungstreffen der deutschen Informatik-Graduiertenkollegs findet 2022 vom 12.-15. Juni wieder auf Schloss Dagstuhl statt. Es wird gemeinschaftlich von den GRKs 'Cybercrime' in Erlangen und 'CONVEY' in München organisiert. Das Leibniz-Zentrum für Informatik auf Schloss Dagstuhl veranstaltet das Treffen an den 3 Tagen in der Fronleichnamswoche. Alle GRKs, die entweder direkt der Informatik zugeordnet sind oder einen starken Informatik-Bezug haben, sind zum Vernetzungstreffen eingeladen.

### BMS Summer School 2022 "Geometry and Topology in a Discrete Setting"

BMS Summer School 2022 "Geometry and Topology in a Discrete Setting" will take place 23 May to 3 June 2022 at Zuse Institute Berlin ZIB. BMS Summer School 2022 will be held as an in person event.

Location: Zuse Institut Berlin Takustr. 7 14195 Berlin

### Jahrestagung 2022 - Joint Annual Workshop 2022 Berlin, Graz, Zürich - April 4 to 8 2022

The Joint Annual Workshop of GRK Facets of Complexity Berlin, DK Discrete Mathematics Graz, and ETH Zürich will take place on April 4 to 8 2022 at Trattnerhof Semriach in Austria.

Location: Der Trattnerhof Hotel im Schöcklland Unterer Windhof 18 8102 Semriach Österreich

### Problem Solving Workshop 2022, Feb 28 to March 4 at Kloster Chorin

The Problem Solving Workshop 2022 will take place from Monday, February 28 to Friday, March 4 2022 at Kloster Chorin . We will work together on selected problemsin small groups. Aim of this workshop is to develop problem-solving skills by working on problems in small teams. The problems will be elementary in the sense that they don't require much prior knowledge.

Location: Infirmarium, Kloster Chorin, Amt Chorin 11a, 16230 Chorin

### Polymake Workshop and Conference at TU Berlin Jan 20-22 2022

The Polymake Workshop and Conference will take place on January 20-22 2022 at TU Berlin. The scientific program and tutorials are on Friday January 21 2022.

### Annual Workshop 2021, December 17-18 Kranichsberg in Erkner

The Annual Workshop 2021 will take place Friday, December 17, and Saturday, December 17, at Hotel Kranichsberg in Berlin-Erkner.

Location: Hotel Kranichsberg An der Schleuse 3-4 15569 Woltersdorf

### Mini Course: "Edge colouring of multigraphs and the Tashkinov trees method"

Schedule: Introduction: Mon Oct 25 14:15-15:15 Lecture 1: Tues Oct 26 14:15-15:45 - Room 025/026* Lecture 2: Thurs Oct 28 8:30-10:00 - Room 032* Lecture 3: Thurs Oct 28 10:30-12:00 - Room 025/026* Lecture 4: Fri Oct 29 10:15-11:45 - Room 007/008*. Program: In this course we will study edge colouring in multigraphs, with an emphasis on the method of Tashkinov trees . A sophisticated generalization of the method of alternating paths, this technique was introduced by Tashkinov to address questions such as the Goldberg-Seymour problem. In particular we will see the theorem of Tashkinov that forms the foundation of the method, and how to apply it to obtain some of the many important results for multigraph edge colouring for which it has been used. Moreover, these applications typically come with efficient algorithms, since the proof of Tashkinov's Theorem is algorithmic. All are welcome to attend. No prior knowledge of edge colouring will be assumed. Detailed description of the program . *Lectures from Tuesday to Friday will take place at: Arnimalle 6. If you are planning to participate, please send a note to: i.brunke@fu-berlin.de .

Location: Introduction: Mon Oct 25 14:15-15:15 Lecture 1: Tues Oct 26 14:15-15:45 - Room 025/026* Lecture 2: Thurs Oct 28 8:30-10:00 - Room 032* Lecture 3: Thurs Oct 28 10:30-12:00 - Room 025/026* Lecture 4: Fri Oct 29 10:15-11:45 - Room 007/008* Lectures 1-4 will take place at Arnimallee 6.

### MATH+ Thematic Einstein Semester on Geometric and Topological Structure of Materials Summer 2021

The MATH+ Thematic Einstein Semester Summer Semester 2021 on Geometric and Topological Structure of Materials will take place April 13 and April 14.

### Jahrestagung 2020 - Annual Workshop 2020

The Annual Workshop will take place from Monday, 28th of September to Thursday, 1st of October 2020 at Burghotel Bad Belzig .

Location: Burghotel Bad Belzig Wittenberger Str. 14 14806 Bad Belzig

### Block Course - Stochastic Topology

The Block Course Stochastic Topology from March 16th to March 20th 2020 is part of the Thematic Einstein Semester on Geometric and Topological Structure of Materials. Taking part summer term 2020. For further information and registration see: Block Course - Stochastic Topology - March 16th-20th Thematic Einstein Semester - Geometric and Topological Structure of Materials

### Problem-Solving Workshop at Kloster Chorin

We will work together on selected problems of Geometric Algorithms in small groups. The location will be the Infirmarium of Kloster Chorin , northeast of Berlin. The purpose of the workshop is to develop problem-solving skills by working on problems in small teams. The problems will be elementary in the sense that they don't require much prior knowledge.

Location: Infirmarium, Kloster Chorin, Amt Chorin 11a, 16230 Chorin

### Einstein Workshop on Polytopes and Algebraic Geometry 2019

Monday Dec. 2 (ZIB) Tuesday Dec. 3 (ZIB) Wednesday Dec. 4 (Hotel Steglitz Int.) 08.30 - 09.00 Registration 09.00 - 10.00 Benjamin Braun Johannes Hofscheier Winfried Bruns Coffee break 10.30 - 10.55 Andrés R. Vindas Meléndez Andrea Petracci Alessio D’Alì 11.00 - 11.25 Davide Bolognini María-Cruz Fernández-Fernández Eliana Duarte 11.30 - 11.55 Carlos Alejandro Alfaro Montufar Oguzhan Yürük Daniel Tamayo Jiménez Lunch 14.00 - 15.00 Alex Fink Thomas Kahle Alexander Borisov 15.10 - 15.35 Filip Cano Córdoba Karin Schaller Marta Panizzut Coffee break 16.10 - 17.10 Matthias Beck Matthias Schymura Fatemeh Mohammadi

### Jahrestagung 2019 - Joint Annual Workshop 2019 Berlin, Graz, Zürich

Die gemeinsame Jahrestagung der Graduiertenkollegs Berlin, Graz und Zürich findet 2019 in Döllnsee statt.

Location: Tagungshotel Döllnsee-Schorfheide Ortsteil Groß Dölln Döllnkrug 2 17268 Templin

### Dagstuhl meeting of German RTGs in Computer Science

This meeting takes place every year from Monday to Wednesday in the week of "Fronleichnam".

Location: Schloss Dagstuhl

### Annual Workshop 2018, December 6-7

Jahrestagung des Graduiertenkollegs ''Facets of Complexity'' 2018.

### Alexander Fink: Minicourse: Algebraic geometry for matroids

I anticipate discussing topics such as my work with Speyer on constructing the Tutte polynomial from torus orbits on a Grassmannian, the "Hodge package" techniques used by Adiprasito, Huh and Katz to prove their log-concavity result, and hyperfields and their Grassmannians. More precise schedules will be posted as the lectures draw nearer. This minicourse will take place on: Monday 22 October - 10:00 am to 12:00 pm Wednesday 24 October - 10:00 am to 12:00 pm Monday 12 November - 10:00 am to 12:00 pm Wednesday 14 November - 10:00 am to 12:00 pm

Location: Technische Universität Berlin Institut für Mathematik Straße des 17. Juni 136 10623 Berlin room MA 212 Mathematikgebäude

### Fall School: Order and Geometry (September 14 - 17, 2018)

The school is addressed to advanced undergraduate and graduate students of Mathematics or Computer Science with interest in Discrete Mathematics and in particular in Partially Ordered Sets and Discrete Geometry. Basic knowledge in discrete mathematics is assumed. The fall school consists of four introductory courses. Each course consists of lectures and exercises.

Location: Gutshof Sauen 70 km SE of Berlin

### Geometric Graph Workshop 2018 (GG-Week)

This is a research workshop where we discuss various problem in groups. The workshop series started as the European Workshop on Pseudotriangulations, and it has been held in different locations. It has broadened its subject area to geometric graphs in general.

Location: Haus Tornow am See, 50 km from Berlin

### Berlin-Poznań-Hamburg Seminar on Combinatorics and Algorithms

This seminar was started by Prof. Michał Karoński from the Adam Mickiewicz University in Poznań and by Prof. Hans Jürgen Prömel (at the time) from Humboldt University of Berlin in the mid 1990's. The event alternates between Berlin, Poznań and (more recently) Hamburg, covering a wide variety of topics in extremal and probabilistic combinatorics, algorithmic discrete mathematics, as well as related fields. This year it takes place on June 8 and 9 at the Free University of Berlin.

Location: Freie Universität Berlin Institut für Mathematik Arnimallee 3 (Room 001) 14195 Berlin