Study Abroad in Germany – Presentation at The University of Waterloo

So, a couple of other exchange students and me were asked to give a short presentation on our home universities and opportunities to go to Germany at The University of Waterloo. This post is an attempt to collect some of the relevant information so others can refer to it later.

One of the worse puns used throughout the presentation
One of the worse puns used throughout the presentation

Continue reading Study Abroad in Germany – Presentation at The University of Waterloo

Problem L of the GCPC 2016 (Maze)

This past Saturday, two friends and I took part in the German Collegiate Programming Contest. Since none of us actually trained much beforehand and it was the first ICPC-like programming contest for two thirds of the team (me included), we were not one of those teams that managed to solve almost all problems, but ended right in the middle of the ranking with a total of three solved problems (even though we were really, really close to solving four 😉 ).

Nevertheless, I’d like to share some insights into one of the problems the organizers of the GCPC came up with. I really like it because there is a beautiful algorithm that you can apply to it and (mostly because) it is somewhat StarTrek related 😉 . The problem I’m talking about is problem L of the GCPC 2016 which you can find in this PDF. The solution of course contains spoilers, so if the problem statement makes you curious I’d recommend giving it a try first and coming back later to see if you found a more elegant solution. If you are a TUM student, you can even run it against all the tests that were used in the contest on TUMJudge.

Continue reading Problem L of the GCPC 2016 (Maze)

Dragonhack 2016: Video and Photos

Earlier this month I attended Dragonhack in beautiful Ljubljana, Slovenia. It was a truly amazing hackathon and I got to know and work with a whole bunch of awesome people. Turns out the organizers made an aftermovie for the event which they have recently released and which I’m gonna share with you today. Try to see if you can spot me in the video, I haven’t found myself in it so far…

However, they also had a professional photographer at the venue who took over 200 photos, so there inevitably are also some photos of us. I’m gonna share the two best photos of us: One of our entire team deep in discussion and one of me on stage demoing our hack with my teammates in the background launching a last-minute effort to get our livedemo to work.

Continue reading Dragonhack 2016: Video and Photos

Brussels 2016 – Mostly pictures

After finishing my thesis I thought I should do something with the rest of my semester break and so I decided to go to Brussels for a few days. I went with two old friends from high school. All three of us had already been to Brussels for a school trip over half a decade ago.
I’m just gonna share a few nice pictures we took (Mostly not mine though 😉 ). As always I’m the only one in the pictures, we Germans tend to value privacy very much 😉

Unrelated PS: As promised, I’m gonna share my term paper from last year on Code Cloning in OpenSource Software in a few days and also show some code cloning offenses that I committed myself over the years (mostly old code from Easy Feed Editor).

Fatal PHP error after upgrading ownCloud

Since I did not want to start the new year with software that isn’t up-to-date (or because I had a little time and didn’t want to do any real work), I decided to update my ownCloud installation to version 8.2.2. Unfortunately, the update tool failed:

Fatal error: Call to a member function getLogger() on a non-object in /path/to/owncloud/lib/public/util.php on line 166

After spending some time trying various stuff, I decided to compare my installation with a fresh one. The only thing I found that was weird was that I had a config.php in the main ownCloud directory (probably left over from a manual update I did a few months back).

ls than mv config.php config_old.php
Renaming the config.php in the main directory helped

So I renamed that one – and voilà. Apparently having a config.php in the main folder causes ownCloud to stop working.
I write this because I didn’t find any solutions of this problem online when I searched.

ATHENS November 2015 in Paris

In the beginning of November I had the amazing opportunity to take part in the ATHENS programme, a program that brings together students from Europe’s leading Technical Universities for one week intensive courses on a variety of subjects.
For me that meant spending a week in Paris and attending a course on Information Extraction at Telecom ParisTech.

After a first meeting organized by our local coordinator at TUM and a trip to the airport the day before because of the flight attendants’ strike it was off to the airport for me. I happened to be on the same flight with three other students that study at TUM as well and with only a slight delay we made it to CISP Kellermann (a hostel in the south of Paris), that was gonna be our home in Paris for a week.
After unpacking my stuff, I walked around the neighborhood with a few fellow students when all of us started receiving phone calls and texts because of the ongoing terrorist attacks in Paris. Back at the CISP all of us had a lot of questions but no answers, so after convincing friends and family that we were safe we decided that there wasn’t much we could do on that day anyway so we called it a night.

Usually, the hosting university organizes tours and visits for the incoming students, but in our case those had to be cancelled, so we organized our own program for the weekend which consisted of prolonged walks around the city, a lot of good food and obscenely many group-selfies.

A bunch of ATHENS students in front of Sacre Cœur
A bunch of ATHENS students in front of Sacre Cœur (photo courtesy of Zhang Jiapei‎)

Continue reading ATHENS November 2015 in Paris

.tk OR If you wait long enough, your free domain is free again

Back in 2009, the first website for Easy Feed Editor was at But since that URL is really long and not very trustworthy, I thought about getting a TLD: Now you have to remember that I was still a high school student back then and I didn’t want to waste any money on a proper domain for a project that might just live for a few more months.

So I kind of went the middle way and got a .tk-Domain. The advantage of those are that they are free. The deal however is that you need to renew your registration once a year or the domain will become available to everyone again.
Being busy with other stuff I forgot to do this last year. A few hours too late I noticed and tried to renew the registration, hoping the no one else had registered it already. Which luckily no one had. However the domain was now considered a Premium Domain and no longer available for free (probably due to having actual traffic). Continue reading .tk OR If you wait long enough, your free domain is free again

Computing the Canonical Cover in Haskell

Today I had a little too much free time on my hand, but didn’t want to start anything that I couldn’t finish before the start of my vacation on Monday. Since I know I will teach two tutorial groups for the intro course on databases at TUM next term, I decided to write a little program that might be helpful when it comes to learning about the canonical cover.
The problem appeared to be very mathematical, so I decided to do it in Haskell. The program itself is kind of boring: You enter a set of functional dependencies and get back the canonical cover. The only usecase I can think of is somebody trying to learn the algorithm and checking if their result is correct.
But writing it sure was a lot of fun! The source code is on Github, a binary for Linux is here.