Blog on David Zollikofer

Building an Order Book from Scratch

Sun, 25 Jan 2026 00:00:00 +0000

I’ve read about market microstructure for years — spreads, adverse selection, market making — but never built any of it. I wanted to see how far I could get using Claude Code as a Socratic tutor.

The answer: further than I expected.

On Organizing My Thoughts and Research

Mon, 29 Dec 2025 12:00:00 +0000

I am a messy person. Always have been. My desk is chaos, my browser has 80+ tabs, and for years my digital notes were scattered across tools I’d forget I even used.

This post is about how I finally stopped fighting that and found something that works. Not a productivity guru revelation — just what happened when I stopped tool-hopping and got honest about what I actually need.

Moving from Machine Learning (ML) to the Intersection of Economics and ML

Sat, 27 Dec 2025 12:00:00 +0000

In the last few months, at least 8 people have asked me in surprise why I moved from pure machine learning into economics. Their reasoning was along the lines of why when AI is booming I am sidestepping and pivoting to something else.

Moving from a Synology DS218j to a DS423

Thu, 20 Mar 2025 18:35:11 +0000

My old NAS that I use for backups and store machine learning datasets I seldom use was becoming frustratingly slow. As a result I swapped out my Synology DS218j (with two 4TB WD Red drives), for a new DS423 with a third 4TB WD Red drive. As I am curious on the real world performance impact I sougth out to benchmark the two set-ups:

Current Personal Cloud Storage Offerings are not Competitive

Mon, 15 Jul 2024 11:57:11 -0400

As someone who relies on multiple computers, I appreciate the convenience that personal cloud storage providers offer. However, I’m surprised by how uncompetitive the current offerings are. Dissatisfied with my Dropbox subscription, I started exploring alternatives and realized this issue is prevalent across the board. I am writing this in hopes that someone who has solved this problem can give me some pointers.

Comments on the "Synthetic Cancer - Augmenting Worms with LLMs" Paper

Tue, 27 Feb 2024 17:31:39 +0100

About a week ago, Benjamin Zimmerman and I have released the “Synthetic Cancer - Augmenting Worms with LLMs” paper for which we have won the first place at the AI Safety Prize.

Throughout the SCSD conference where we presented our work we have been asked a few questions by fellow researchers, journalists as well as the informed public. As a result I wanted to use this space to write down some of my thoughts.

Moving from the X1 Carbon 9th Gen running Fedora to a Macbook Pro 14 with M2 Pro

Thu, 11 Jan 2024 12:45:15 +0000

As I will be going to the US for a few months this year, I knew I would not be able to take a huge Desktop PC with me. Hence, I started researching for solutions.

The MacBook Pro 14 with M2 Pro seemed like a good fit. It is a very powerful machine with great battery life, and given that the successor with the M3 Pro is already out, it was possible to get a good deal on the M2 Pro.

Climate Tracker with Ruuvi Tag

Mon, 21 Aug 2023 00:00:00 +0000

As there is currently a heatwave rolling over Switzerland, I wanted to get detailed information on temperature and humidity. While researching some solutions to automatically record these values for multiple places wirelessly, I came across Ruuvi Tags.

In the following tutorial I will outline the steps needed to create a Raspberry Pi based temperature, humidity, and air pressure recorder including a nice graphical front-end. There are already plenty of similar tutorials online but most are either incomplete or a few years old (i.e. following them will get you stuck at some point), hence I wanted to document my journey with the Ruuvi Tags.

Some Thoughts on the X1 Carbon 9th Gen with Linux

Wed, 22 Feb 2023 00:00:00 +0000

I used to have a Dell XPS 13 developer edition with a 4k screen. I was utterly disappointed with the 3-4h battery life and the weight of the laptop, hence once I saw a good offer for a used Lenovo X1 9th Gen, I couldn’t resist.

Sane Explanation of Change of Bases

Thu, 20 Feb 2020 00:00:00 +0000

The following is an explanation how changes of bases work in vector spaces with a focus on building intuition.

Implementing a Semaphore in Java

Sat, 27 Apr 2019 00:00:00 +0000

Today we will take a glimpse at semaphores and have a look at an implementation based on locks.

What is a semaphore?

A semaphore is basically a lock that allows multiple processes to enter a critical section at the same time. As an example one could see car park barriers as semaphores. If a car park has 100 lots, the barrier will only allow 100 cars into the car park at the same time. After a car has left, we expect the barrier to allow a new car in.

Implementation of Sorting Algorithms in Java

Tue, 05 Feb 2019 00:00:00 +0000

This document is a list of common sorting algorithms and their implementations in Java. The algorithms have been written by myself. I have tested them with the JUnit tests you can find at the end of this article, however, I do not guarantee that the implementations are 100% correct. Feel free to comment below or write me an email if you find a mistake.

A short proof of Cantor's theorem

Wed, 31 Oct 2018 00:00:00 +0000

Cantor’s theorem states that for any set $S$ we have $S \preceq \mathcal{P}(S)$ and $S \nsim \mathcal{P}(S)$. In words this means that the cardinality of $\mathcal{P}(S)$ is strictly bigger than the cardinality of $S$.

Unlike some of my other posts, this one is strictly mathematical.

Writing a Sudoku Solver in Python

Sun, 02 Sep 2018 00:00:00 +0000

Pretty much every free newspaper you find comes with a sudoku puzzle. Depending on the difficulty it might take you a considerable amount of time to solve them. As a result I wanted to write an algorithm which could do that for me within seconds.

Building an API based temperature sensor

Wed, 15 Aug 2018 00:00:00 +0000

The goal of this short summary is to explain how you can build a small API based temperature sensor that costs less than 10$ and can be used anywhere. I use this sensor at my office to log the temperature and then display it on a smart dashboard.

Automating Cross Compiling Go Programs on Linux

Mon, 02 Jul 2018 00:00:00 +0000

Programs written in Go can be compiled for a variety of different targets. Cross compiling is easy, but takes a lot of effort.

In order to automate cross compilation the following Ruby script is built to take that burden off you.