From Matfyz to Cambridge: An Interview with Tymofii Reizin
Tymofii Reizin was born in Ukraine and, if it were not for the war, everything might have been different. When considering university options, Tymofii heard about Matfyz from a friend and moved to the Czech Republic to study computer science. After graduating, he was accepted to the University of Cambridge. In this interview, Tymofii reveals what Matfyz gave him, what it is like to study and do research in several different countries, and even what makes a good programming problem.
In 2024, Tymofii Reizin successfully completed a bachelor’s degree in Computer Science at Matfyz. In his well-received bachelor’s thesis, he examined transformers, that is, neural networks excelling at tasks such as natural language processing, audio processing, and computer vision. Examples of models built on transformers include ChatGPT, BERT, GPT-4, Gemini, Claude3, and more.
The study’s primary focus was on the attention mechanism, which contextualises individual words. Reizin explored a theoretical hardness result indicating that standard attention cannot be approximated in sub-quadratic time with respect to input length. However, Tym also investigated alternatives that can compute in linear time. The experiments carried out compared the accuracy of various attention implementations, as shown in the graph below.
After Matfyz, Tymofii switched to mathematics and has been pursuing his master’s degree at the University of Cambridge, where he started as a research assistant and was awarded the Trinity Eastern European Bursary. Although it cannot be described as a significant change of field, something did change for Tym after all, and he became more drawn to a theoretical approach rather than running experiments. His main interest has become combinatorics.
Outside of school, Tymofii has participated in many exciting projects. One of these is the Ukrainian Olympiad in Artificial Intelligence 2025, for which he designed all the problems. “The best problems are those where you spend more time thinking than implementing the solution,” describes Tym. Subsequently, he also trained the Ukrainian national team to compete at the international level.
Tymofii Reizin ranks among the top 0.5% worldwide on the programming platform Codeforces. Despite how competitive that sounds, Tymofii reassured me that completing a task does not have to be cutthroat. Before or after any programming competition there is a friendly atmosphere, and people share their solutions with each other. And if you struggle and get stuck on one problem? Just move on to another one and eventually return where you lost it, Tym concludes in our interview. Enjoy our podcast!
