Awards

• Winner of the Parallel SSSP track at the FastCode Programming Challenge at PPoPP 2025.
• Best Paper Award at Euro-Par 2024.

Publications

• Elastic Relaxation of Concurrent Data Structures (TPDS 2025). Kåre von Geijer, Philippas Tsigas.
  • Links: Open access paper, published artifact.
• Relax and don't Stop: Graph-Aware Asynchronous SSSP (FCPC at PPoPP 2025). Marco D'Antonio, Kåre von Geijer, Thai Son Mai, Philippas Tsigas, Hans Vandierendonck.
  • Won the competition for fastest parallel SSSP solver.
• Balanced Allocations over Efficient Queues: A Fast Relaxed FIFO Queue (PPoPP 2025). Kåre von Geijer, Philippas Tsigas, Elias Johansson, Sebastian Hermansson.
  • Links: Open access paper, accepted manuscript, published artifact.
• How to Relax Instantly: Elastic Relaxation of Concurrent Data Structures (Euro-Par 2024). Kåre von Geijer, Philippas Tsigas.
  • Won the Euro-Par 2024 Best Paper award.
  • Links: Published paper, accepted manuscript, extended pre-print, published artifact.

Master Thesis Supervision

I have had the pleasure to supervise a few students through their master's theses. These projects have often led to some interesting results, and have been very enjoyable to work with. Here is the list of projects I've supervised (links included for the ones available online):

• A Faster Breadth-First Search on Sparse Graphs (2025). Simon Holst, Johan Selin.
• Efficiently Calculating Relaxation Errors (2025). Elis Kleen, Victor Olin.
• Accurate Linearizations for Relaxed FIFO queues (2025). Ida Dahl, Hanna Schaff.
• Lock-Free Queues in Rust (2025) (GitHub repo). Gustavn Seffel, Willaim Berg.
• Progress-Based Distributed Queues (2024). Sebastian Hermansson, Elias Johansson.
• Lock-Free Concurrency in Rust (2024). Lilly Jinstrand, Marcus Julin.
• Granular Contention Avoiding Priority Queues in Rust (2024). Sebastian Nielsen, Rasmus Rosengren.
• Relaxed Priority Queue & Evaluation of Locks (2023). Andreas Rudén, Ludvig Andersson.