About

I am currently pursuing a PhD at the DTAI lab of KU Leuven, focusing on the intersection of Constraint Programming and Large Language Models, under the supervision of Prof. Tias Guns. My research explores how large language models can support constraint modelling, from translating natural-language problem descriptions into symbolic models to improving their solver efficiency.

Before starting my PhD, I worked as a software engineer in the industry, where I developed enterprise-level applications. I hold a Master's in Computer Science from KU Leuven, majoring in AI, and a Bachelor's in Informatics & Telecommunications from NKUA, majoring in CS.

Publications

• [Preprint] LLM-Guided Evolutionary Search for Constraint Model Reformulation to Improve Solver Efficiency. arXiv:2607.28268 (2026).
  Kostis Michailidis, Dimos Tsouros, Nguyen Dang, and Tias Guns.
  Paper (PDF) | Slides (PDF)
• CP-Bench: Evaluating Large Language Models for Constraint Modelling. In European Conference on Artificial Intelligence (ECAI 2025). Frontiers in Artificial Intelligence and Applications, Volume 413, pp. 861-868 (2025).
  Kostis Michailidis, Dimos Tsouros, and Tias Guns.
  Paper (PDF) | Poster (PDF) | Code
• Constraint Modelling with LLMs Using In-Context Learning. In 30th International Conference on Principles and Practice of Constraint Programming (CP 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 307, pp. 20:1-20:27, Schloss Dagstuhl -- Leibniz-Zentrum für Informatik (2024). https://doi.org/10.4230/LIPIcs.CP.2024.20
  Kostis Michailidis, Dimos Tsouros, and Tias Guns.
  Paper (PDF) | Presentation (Video) | Slides (PDF) | Poster (PDF) | Code

Talks & Presentations

• LLM-Guided Evolutionary Search for Model Reformulation towards Solver Efficiency. Workshop: LLMs meet Constraint Solving (LLM-Solve), CP/FLoC 2026, Lisbon, Portugal (July 19, 2026).
  Kostis Michailidis, Dimos Tsouros, Nguyen Dang, and Tias Guns.
  Workshop | Slides (PDF)
• CP-Bench: Benchmarking LLMs for CP Model Generation (based on the ECAI 2025 paper). Workshop: LLMs meet Constraint Solving (LLM-Solve), CP/SAT 2025, Glasgow, Scotland (August 11, 2025).
  Kostis Michailidis, Dimos Tsouros, and Tias Guns.
  Workshop | Slides (PDF)

Software & Resources

• DCP-Bench-Open: Interactive Catalogue & Code
• Take a look at our live demo of ChatOpt: A Chatbot for Constraint Modelling.
• CP-Bench (archived): Dataset & Leaderboard

Teaching & Service

• Teaching Assistant (TA) for Constraint Solving (CoS), Master of Computer Science, KU Leuven, 2025.
• Teaching Assistant (TA) for Declarative Problem Solving Paradigms for AI (DPSPAI), Master of Computer Science, KU Leuven, 2024.
• Co-supervision of Master's thesis students at KU Leuven.
• Reviewing for journals and conferences including ACM Computing Surveys, AAAI, and CPAIOR.

Awards

• Best Poster Award for the paper "Constraint Modelling with LLMs Using In-Context Learning", CP 2024, Doctoral Program.