Andreas Grigorjew

About me

Welcome! I am a doctoral student at the University of Helsinki in the Department of Computer Science, supervised by Alexandru I. Tomescu. I am part of the Graph Algorithms Team.

My research interests broadly lie in theoretical computer science and include graph theory, algorithms and combinatorics.
In spring 2025, I visited the Applied Algorithms Group at the Montana State University.

In my free time, I enjoy bouldering and spending time in nature. I am also trying to master playing the violin and the Finnish language.

You are welcome to contact me via email: contact [at] andreasgrigorjew [dot] de (PGP key).

Research

Publications and preprints

• Andreas Grigorjew, Wanchote Jiamjitrak, Brendan Mumey, Alexandru I. Tomescu
  Parameterised Approximation and Complexity of Minimum Flow Decompositions
  arXiv, 2024 (view preprint)
  
• Andreas Grigorjew, Fernando H. C. Dias, Andrea Cracco, Romeo Rizzi, Alexandru I. Tomescu
  Accelerating ILP solvers for Minimum Flow Decompositions through search space and dimensionality reductions
  SEA 2024 - International Symposium on Experimental Algorithms, 14:1-14:19, 2024 (view)
  Best paper award runner-up
• Manuel Cáceres, Massimo Cairo, Andreas Grigorjew, Shahbaz Khan, Brendan Mumey, Romeo Rizzi, Alexandru I. Tomescu, Lucia Williams
  Width Helps and Hinders Splitting Flows
  ACM Transactions on Algorithms, 20(2), 1--20, 2024 (view extended version)
  ESA 2022 - European Symposium on Algorithms (Track A), 31:1--31:14, 2022 (view)
• Andreas Grigorjew, Artur Gynter, Fernando Dias, Benjamin Buchfink, Hajk-Georg Drost*, Alexandru I. Tomescu*
  Sensitive inference of alignment-safe intervals from biodiverse protein sequence clusters using EMERALD
  Genome Biology 24, 168, 2023 (view)
  *Equal contribution

Software

• Optimized FD: An optimized flow decomposition solver using Integer Linear Programming, for exact optimum and heuristic solutions (GitHub).
  Flow decompositions are used e.g. for RNA transcriptict assembly or viral strain reconstruction.
• EMERALD: a protein sequence aligner that finds safety windows, protein regions preserved in the suboptimal alignment space (GitHub).

Teaching

I was a teaching assistant in the following courses holding exercise classes:

• Models of Computation, spring 2024 (Helsinki)
• Models of Computation, spring 2023 (Helsinki)
• Elements of Bioinformatics, autumn 2022 (Helsinki)
• Design and analysis of algorithms, autumn 2021 (Helsinki)
• Mathematik für Data Science und Physik Studierende I, winter 2021 (Erlangen)
• Analysis III, winter 2019 (Erlangen)
• Theorie der Programmierung, summer 2019 (Erlangen)
• Theorie der Programmierung, summer 2018 (Erlangen)

Education

• since April 2021: Doctoral student in the Department of Computer Science at the University of Helsinki
• October 2018 until March 2021: Master of Science in Mathematics at the Friedrich-Alexander-Universität Erlangen-Nürnberg
• January 2020 until May 2020: Exchange semester at the University of Helsinki
• October 2015 until July 2018: Bachelor of Science in Mathematics at the Friedrich-Alexander-Universität Erlangen-Nürnberg