About

I am a postdoctoral researcher at Athena Research Center, working on algorithms and data structures for high-dimensional data.

My research is in high-dimensional computational geometry: randomized algorithms and data structures, similarity search, and time series analysis. Most of my work concerns nearest neighbor and clustering problems, and solutions that come with theoretical guarantees — complexity bounds, proofs of correctness, or both.

Until recently I was at Archimedes. Before that I worked at the Information Management Systems Institute, with Manolis Terrovitis, on the research project MORE: Management of Real-Time Energy Data. Prior to that I was a postdoctoral researcher at the University of Bonn with Prof. Anne Driemel, and an associate member of the Hausdorff Center for Mathematics. I obtained my PhD in 2019 from the National and Kapodistrian University of Athens under the supervision of Prof. Ioannis Z. Emiris.

Interests — high-dimensional geometry, randomized algorithms and data structures, similarity search, clustering, time series, Fréchet and dynamic time warping distances.

Publications

• 2026

  Time Series Decomposition using the Fréchet Distance

  Anne Driemel, Jan Höckendorff, Ioannis Psarros, Christian Sohler

  ESA 2026to appear

• 2026

  Near Linear Time Approximation Schemes for Clustering of Partially Doubling Metrics

  Anne Driemel, Jan Höckendorff, Ioannis Psarros, Christian Sohler, Di Yue

  ICALP 2026doiarXiv

• 2026

  Space-Efficient Approximate Spherical Range Counting in High Dimensions

  Andreas Kalavas, Ioannis Psarros

  SoCG 2026doiarXiv

• 2025

  Random Projections for Curves in High Dimensions

  Ioannis Psarros, Dennis Rohde

  Discrete & Comput. Geom.74(2): 374–398doi

• 2025

  Faster Approximation Algorithms for k-Center via Data Reduction

  Arnold Filtser, Shaofeng H.-C. Jiang, Yi Li, Anurag Murty Naredla, Ioannis Psarros, Qiaoyuan Yang, Qin Zhang

  ICML 2025proceedingsarXiv

• 2025

  A near-linear time approximation scheme for (k,ℓ)-median clustering under the discrete Fréchet distance

  Anne Driemel, Jan Höckendorff, Ioannis Psarros, Christian Sohler

  preprintarXiv

• 2025

  A Query-Driven Approach to Space-Efficient Range Searching

  Dimitris Fotakis, Andreas Kalavas, Ioannis Psarros

  preprintarXiv

• 2024

  Fast Approximations and Coresets for (k,ℓ)-Median Under Dynamic Time Warping

  Jacobus Conradi, Benedikt Kolbe, Ioannis Psarros, Dennis Rohde

  SoCG 2024doiarXiv

• 2023

  Near-neighbor preserving dimension reduction via coverings for doubling subsets of ℓ₁

  Ioannis Z. Emiris, Vasilis Margonis, Ioannis Psarros

  Theor. Comput. Sci.942: 169–179doi

• 2023

  Random Projections for Curves in High Dimensions

  Ioannis Psarros, Dennis Rohde

  SoCG 2023doiarXiv

• 2023

  A Tool for Visual Exploration and Analysis of Solar Photovoltaic Module Data

  Vassilis Stamatopoulos, Stavros Maroulis, Konstantinos Kozanis, Ioannis Psarros, George Papastefanatos, Giorgos Giannopoulos, Manolis Terrovitis

  BigVis @ EDBT/ICDT 2023pdf

• 2023

  Data-driven soiling detection in PV modules

  Alexandros Kalimeris, Ioannis Psarros, Giorgos Giannopoulos, Manolis Terrovitis, George Papastefanatos, Gregory Kotsis

  preprintarXiv

• 2022

  Tight Bounds for Approximate Near Neighbor Searching for Time Series under the Fréchet Distance

  Karl Bringmann, Anne Driemel, André Nusser, Ioannis Psarros

  SODA 2022517–550doiarXiv

• 2022

  Approximating Length-Restricted Means Under Dynamic Time Warping

  Maike Buchin, Anne Driemel, Koen van Greevenbroek, Ioannis Psarros, Dennis Rohde

  WAOA 2022225–253doiarXiv

• 2022

  Machine Learning Platform for Extreme Scale Computing on Compressed IoT Data

  S. Tirupathi, D. Salwala, G. Zizzo, A. Rawat, M. Purcell, S. K. Jensen, C. Thomsen, N. Ho, C. E. Muñiz-Cuza, J. Brusokas, T. B. Pedersen, G. Alexiou, G. Giannopoulos, P. Gidarakos, A. Kalimeris, S. Maroulis, G. Papastefanatos, I. Psarros, V. Stamatopoulos, M. Terrovitis

  IEEE Big Data 20223179–3185doi

• 2021

  The VC Dimension of Metric Balls under Fréchet and Hausdorff Distances

  Anne Driemel, André Nusser, Jeff M. Phillips, Ioannis Psarros

  Discrete & Comput. Geom.66(4): 1351–1381doi

• 2021

  ANN for Time Series Under the Fréchet Distance

  Anne Driemel, Ioannis Psarros

  WADS 2021315–328doi

• 2020

  High-Dimensional Approximate r-Nets

  Zeta Avarikioti, Ioannis Z. Emiris, Loukas Kavouras, Ioannis Psarros

  Algorithmica82(6): 1675–1702doi

• 2020

  Products of Euclidean Metrics, Applied to Proximity Problems among Curves: Unified Treatment of Discrete Fréchet and Dynamic Time Warping Distances

  Ioannis Z. Emiris, Ioannis Psarros

  ACM Trans. Spatial Algorithms Syst.6(4): 27:1–27:20doi

• 2020

  (2+ε)-ANN for time series under the Fréchet distance

  Anne Driemel, Ioannis Psarros

  manuscriptarXiv

• 2019

  Near-Neighbor Preserving Dimension Reduction for Doubling Subsets of ℓ₁

  Ioannis Z. Emiris, Vasilis Margonis, Ioannis Psarros

  APPROX/RANDOM 2019doiarXiv

• 2019

  The VC Dimension of Metric Balls under Fréchet and Hausdorff Distances

  Anne Driemel, Jeff M. Phillips, Ioannis Psarros

  SoCG 2019doiarXiv

• 2019

  Sublinear data structures for short Fréchet queries

  Anne Driemel, Ioannis Psarros, Melanie Schmidt

  manuscriptarXiv

• 2019

  Proximity problems for high-dimensional data

  Ioannis Psarros — PhD thesis, National and Kapodistrian University of Athens (advisor: Ioannis Z. Emiris)

  thesislink

• 2018

  Randomized Embeddings with Slack and High-Dimensional Approximate Nearest Neighbor

  Evangelos Anagnostopoulos, Ioannis Z. Emiris, Ioannis Psarros

  ACM Trans. Algorithms14(2): 18:1–18:21doi

• 2018

  Products of Euclidean Metrics and Applications to Proximity Questions among Curves

  Ioannis Z. Emiris, Ioannis Psarros

  SoCG 2018doiarXiv

• 2017

  High-dimensional approximate r-nets

  Georgia Avarikioti, Ioannis Z. Emiris, Loukas Kavouras, Ioannis Psarros

  SODA 201716–30doiarXiv

• 2016

  Practical linear-space Approximate Near Neighbors in high dimension

  Georgia Avarikioti, Ioannis Z. Emiris, Ioannis Psarros, Georgios Samaras

  manuscriptarXivDolphinn (C++)DolphinnPy

• 2015

  Low-Quality Dimension Reduction and High-Dimensional Approximate Nearest Neighbor

  Evangelos Anagnostopoulos, Ioannis Z. Emiris, Ioannis Psarros

  SoCG 2015436–450doiarXiv

• 2014

  Counting Euclidean embeddings of rigid graphs

  Ioannis Z. Emiris, Ioannis Psarros

  manuscriptarXiv

A complete and continuously updated list is available on dblp.

Teaching

• Algorithms & Complexity — University of the Peloponnese · Fall 2026
• Teaching assistant — Geometric Data Analysis, Computational Geometry, Advanced Geometric Algorithms, Randomized Algorithms, Software Development for Algorithmic Problems · Univ. of Athens
• Co-supervision of several undergraduate and postgraduate dissertations

Service & research visits

Sub-reviewer for FOCS, SODA, SoCG, ESA, SWAT and LATIN, and for the journals TCS and JoCG.

• University of Illinois at Chicago, hosted by Anastasios Sidiropoulos — geometric data science, embedding properties of neural networks, nearest neighbor structures for asymmetric distances · Apr 2018 – Jun 2019
• Shapes AI, London — AI for 3D shapes: neural network methods for classification and retrieval · Dec 2017 – Mar 2018
• Sorbonne University, Paris, hosted by Elias Tsigaridas · May 2016
• Inria Nancy – Grand Est, advised by Xavier Goaoc and Guillaume Moroz — computer algebra for constant-size geometric problems · Apr – Jul 2013