Divide and Conquer

About lasagne, splitting methods and your favourite film

The ‘Divide and Conquer’-principle was already used in the Roman foreign policy. The politicians and warlords of the ancient world noticed that a large group of people can be easier controlled or even conquered if you split them up into several smaller groups.

show an animation of the quicksort algorithm, descriped in the text

Quicksort algorithm: source
CC BY-SA3.0 Roland H.

Luckily the ancient times are long gone, but the principle remains, in particular in computer science.  Many algorithms are based on the idea of splitting a task into several easy-to-handle parts. After solving these simpler parts, the solution of the full problem needs to be reconstructed from the solutions of these subproblems. So, it is possible to ‘conquer’ a complex task.

A famous example is the well-known Quicksort algorithm to sort a list of numbers. You start by picking one number in the list (the pivot element) and compare it to every other number of the list. If the other number is smaller, we put it on the left side of our pivot element, if it is larger, we put it on the right side. Thus, we get two sublists, one with smaller and one with larger numbers than the pivot element. We continue to sort these sublists in the same way with new pivot numbers from the sublists. The complete list is sorted when all sublists are sorted.

You may wonder what this is all about and how this is related to our CRC?

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Im Fokus: Rainer Mandel

Am 1. Juli 2016 tritt Rainer Mandel seine neue Position als Nachwuchsgruppenleiter im Rahmen des SFBs an. Für mindestens drei Jahre wird er mit seiner Forschung unseren SFB bereichern und erstmals Promovierende betreuen. Wir haben ihm einige Fragen gestellt.


Wie sind Sie zur Mathematik gekommen und welches waren die bisher bedeutendsten Schritte in Ihrer beruflichen Laufbahn? Continue Reading →

Ein Mekka für Mathematiker – Oberwolfach

Mathematisches Forschungsinstitut Oberwolfach

“Tübingen, in der Nähe von Oberwolfach”, was für viele Menschen wie eine absurde Ortsbeschreibung klingt, ist unter Mathematikern absolut verständlich. Denn im beschaulichen Oberwolfach im Schwarzwald befindet sich das Mathematische Forschungsinstitut Oberwolfach (MFO). Es bietet Platz für Workshops, Sommerschulen und Forschungsaufenthalte und beherbergt eine der größten mathematischen Bibliotheken der Welt, ein Mekka für Mathematiker. Ende März nahmen sechs von uns am Workshop “Geometric Numerical Integration” teil: neben mir die beiden Organisatoren Marlis Hochbruck und Christian Lubich sowie Volker Grimm, Tobias Jahnke und Katharina Schratz.

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What actually is cat content?

Welcome to the seminar - poster

photo by Tobias Maier

We, thirteen fearless mathematicians, started our journey into the world of online science communication. The goal was always in our minds: inspiration of the public and representation of our research center. We had to plan our routes, get to know fabulous lookouts and dangerous cliffs and were thrown into the deep to learn to fly.


Our guide Tobias Maier, photo by Gudrun Thäter

Like every journey, we began with packing our bags by participating at a kick-off workshop with the NaWik. Our guide Dr. Tobias Maier, biochemist and writer of the blog WeiterGen, was always at our side. He helped us though the difficult starting process. First we worked out aims and target groups for our online presentation. We want to be visible for you, our reader. We want to fascinate you about our research, the beauty of mathematics and to report from our activities like workshops, conferences and summer schools. A particular challenge is to deal with different target audiences. Naturally, we want to be visible for other scientists and students to inform them and to find new collaborations. In addition we want to address a general public, journalists, school kids or our families and friends. Mathematics is everywhere in our everyday life, but it often hides itself like a shy animal. We want to help changing the peoples attitude towards mathematics and explain to them why our research can make a difference.



photo by Tobias Maier

To reach the different target audiences, Tobias Meier gave us a walk-through to various kinds of online media. In a lively debate we discussed advantages and disadvantages of Twitter, Facebook and others, and learned how to analyze our impact in such media. We are a heterogeneous group with professors, post doctoral researchers and also PhD students, thus, the students used their chance to turn the tables and to bring their expertise to bear. We discussed question like: Why do we need a facebook account if we already have a blog? How do mentions on twitter work? Or how can we find pictures to illustrate our blog articles without infringing copyright laws?

We had also had two sessions with external guests. Dr. Gudrun Thäter, a mathematician from our department and producer of the podcast Modellansatz, talked about math podcasts. A cooperation between this podcast and the CRC just started, since the current episodes (Modell080 f.) discuss the project ´Cooking Math’, a cooperation between students of Hochschule fuer Gestaltung and PhD-students of the CRC. On the other hand, Denis Elbl provided an insight into the KIT online team consisting of a facebook and a twitter account. He gave us useful tips how to manage accounts in social networks and shared his experience on feedback and comments with us.

In the last session we started our journey, hoisted our sails. The blog team set up this blog with a first blog entry. The social media team created a facebook and a twitter account. The video team started an youtube channel. Every team has milestones on their first route, which they want to achieve. So, come back soon to visit us again. It will be worth while!

And for those who expected to find some cat content here: I’m sorry, we decided to just have dog content here.

dog Gonzo

Gonzo, dog of the CRC-speaker Marlis Hochbruck, photo by: Dana Geithner