About Me
Hello! I’m Dimitri, a third-year PhD student in Computer Science at Johns Hopkins University (JHU), advised by Prof. Nicolas Loizou. I’m broadly interested in large-scale optimization and machine learning. My current research focuses on adaptive methods for minimization problems, with applications in deep learning and large language models.
Before JHU, I earned a BSc in Mathematics from the National and Kapodistrian University of Athens (NKUA), a MSc in Data Science and Machine Learning from the National Technical University of Athens (NTUA), and a MSc in Mathematics from Göttingen University.
Research
Adaptive Sharpness-Aware Minimization with a Polyak-type Step Size: A Theory-Grounded Scheduler
Under Submission
Dimitris Oikonomou, Nicolas Loizou
Safeguarded Stochastic Polyak Step-Sizes for Non-smooth Optimization: Robust Performance Without Small (Sub)Gradients
In arXiv:2512.02342, 2025
Dimitris Oikonomou, Nicolas Loizou
Analysis of an idealized stochastic polyak method and its application to black-box model distillation
In arXiv:2504.01898, 2025
Robert Gower, Guillaume Garrigos, Nicolas Loizou, Dimitris Oikonomou, Konstantin Mishchenko, Fabian Schaipp
Sharpness-Aware Minimization: General Analysis and Improved Rates
In the 13th International Conference on Learning Representations (ICLR 2025), Code
Dimitris Oikonomou, Nicolas Loizou
Stochastic Polyak Step-sizes and Momentum: Convergence Guarantees and Practical Performance
In the 13th International Conference on Learning Representations (ICLR 2025), Code
Dimitris Oikonomou, Nicolas Loizou
Selected Honors & Awards
Mathematical Olympiads
- International Mathematical Olympiad (IMO): Bronze Medal @ Santa Marta, Colombia, 2013
- Greek Mathematical Olympiad: Silver Medal @ Athens, Greece, 2014
- Greek Mathematical Olympiad: Bronze Medal @ Athens, Greece, 2013
Scholarships
- Hellenic Post Scholarship: 2015-2019
- DAAD Scholarship: 2019-2020
- JHU MINDS Fellowship: 2024, 2025
Invited Talks & Posters
- International Conference on Learning Representations (ICLR 2025), Singapore (2x Poster)
- SIAM Conference on Optimization 2026, Edinburgh, UK
Teaching & Professional Service
- Teaching Assistant: Computer Vision @ JHU, Fall 2024
- Reviewer: IEEE Transactions on Signal Processing, ICML, NeurIPS, ICLR