My research interests mainly revolve around Algorithmic Game Theory.  I also enjoy working in Computational Social Choice and in the intersection of Theoretical Computer Science and Economics. I study the computational complexity and also exact/approximation algorithms of problems in these fields.

A full list of publications and manuscripts can be found on DBLP and Google Scholar.

Conference papers

• Constant Inapproximability for Fisher Markets (proceedings, video)
  EC 2024, 25th ACM Conference on Economics and Computation
  with Argyrios Deligkas, John Fearnley, and Alexandros Hollender 

• On the Smoothed Complexity of Combinatorial Local Search (proceedings, arXiv)
  ICALP 2024, 51st International Colloquium on Automata, Languages, and Programming
  with Yiannis Giannakopoulos, and Alexander Grosz 

• Optimization of Trading Strategies Using a Genetic Algorithm Under the Directional Changes Paradigm with Multiple Thresholds (proceedings)
  CEC 2023, IEEE Congress on Evolutionary Computation
  with Ozgur Salman, and Michael Kampouridis

• Tight Inapproximability for Graphical Games (proceedings, arXiv)
  AAAI 2023, 37th AAAI Conference on Artificial Intelligence
  with Argyrios Deligkas, John Fearnley, and Alexandros Hollender 

• Pure-Circuit: Strong Inapproximability for PPAD (proceedings, arXiv, video)
  FOCS 2022, 63rd Annual Symposium on Foundations of Computer Science
  with Argyrios Deligkas, John Fearnley, and Alexandros Hollender 

• Constant Inapproximability for PPA (proceedings, arXiv, video)
  STOC 2022, 54th Annual ACM Symposium on Theory of Computing
  with Argyrios Deligkas, John Fearnley, and Alexandros Hollender 

• Pizza Sharing is PPA-hard (proceedings, arXiv, video)
  AAAI 2022, 36th AAAI Conference on Artificial Intelligence
  with Argyrios Deligkas, and John Fearnley

• Walrasian Equilibria in Markets with Small Demands (proceedings, arXiv, video)
  AAMAS 2021, 20th International Conference on Autonomous Agents and MultiAgent Systems
  with Argyrios Deligkas, and Paul G. Spirakis

• Connected Subgraph Defense Games (proceedings, arXiv)
  SAGT 2019, 12th International Symposium on Algorithmic Game Theory
  with Eleni C. Akrida, Argyrios Deligkas, and Paul G. Spirakis

• Computing Exact Solutions of Consensus Halving and the Borsuk-Ulam Theorem (proceedings, arXiv)
  ICALP 2019, 46th International Colloquium on Automata, Languages, and Programming
  with Argyrios Deligkas, John Fearnley, and Paul G. Spirakis

• Approximating the Existential Theory of the Reals (proceedings, arXiv, video)
  WINE 2018, 14th International Conference on Web and Internet Economics
  with Argyrios Deligkas, John Fearnley, and Paul G. Spirakis

• Strategic Contention Resolution in Multiple Channels (proceedings, arXiv)
  WAOA 2018, 16th International Workshop on Approximation and Online Algorithms
  with George Christodoulou, and Paul G. Spirakis

• Short Paper: Strategic Contention Resolution in Multiple Channels with Limited Feedback (proceedings, arXiv)
  SAGT 2018, 11th International Symposium on Algorithmic Game Theory
  with George Christodoulou, and Paul G. Spirakis

• Mutants and Residents with Different Connection Graphs in the Moran Process (proceedings, arXiv)
  LATIN 2018, 13th Latin American Symposium on Theoretical Informatics
  with Sotiris E. Nikoletseas, Christoforos L. Raptopoulos, and Paul G. Spirakis

• Existence of Evolutionarily Stable Strategies Remains Hard to Decide for a Wide Range of Payoff Values (proceedings, arXiv)
  CIAC 2017, 10th International Conference on Algorithms and Complexity
  with Paul G. Spirakis
  
  

Journal papers

• A Genetic Algorithm for the Optimization of Multi-Threshold Trading Strategies in the Directional Changes Paradigm
  (to appear) Artificial Intelligence Review 2025
  with Ozgur Salman, and Michael Kampouridis

• On the Smoothed Complexity of Combinatorial Local Search (article)
  MOR 2025, Mathematics of Operations Research
  with Yiannis Giannakopoulos, and Alexander Grosz

• Pizza Sharing is PPA-hard (article)
  ToCT 2025, ACM Transactions on Computation Theory
  with Argyrios Deligkas, and John Fearnley

• Constant Inapproximability for PPA (article)
  SICOMP 2025, SIAM Journal on Computing
  with Argyrios Deligkas, John Fearnley, and Alexandros Hollender 

• Pure-Circuit: Tight Inapproximability for PPAD (article)
  JACM 2024, Journal of the ACM, Volume 71, Issue 5, Article 31
  with Argyrios Deligkas, John Fearnley, and Alexandros Hollender 

• Approximating the Existential Theory of the Reals (article)
  JCSS 2022, Journal of Computer and System Sciences, Volume 125: 106-128
  with Argyrios Deligkas, John Fearnley, and Paul G. Spirakis

• An Extension of the Moran Process Using Type-specific Connection Graphs (article)
  JCSS 2022, Journal of Computer and System Sciences, Volume 124: 77-96
  with Sotiris E. Nikoletseas, Christoforos L. Raptopoulos, and Paul G. Spirakis

• Connected Subgraph Defense Games (article)
  Algorithmica 2021
  with Eleni C. Akrida, Argyrios Deligkas, and Paul G. Spirakis

• Computing Exact Solutions of Consensus Halving and the Borsuk-Ulam Theorem (article)
  JCSS 2021, Journal of Computer and System Sciences, Volume 117: 75-98
  with Argyrios Deligkas, John Fearnley, and Paul G. Spirakis

Surveys

• Multi-Agent Systems for Computational Economics and Finance (article, arXiv)
  AI Communications 2022, Volume 35, no. 4, pp. 369-380
  with Michael Kampouridis, Panagiotis Kanellopoulos, Maria Kyropoulou, and Alexandros A. Voudouris 

Program committees

• International Conference on Autonomous Agents and Multiagent Systems (AAMAS) 2025

• European Conference on Artificial Intelligence (ECAI) 2024, 2025

• International Joint Conference on Artificial Intelligence (IJCAI) 2021, 2022, 2023, 2024

• Conference on Artificial Intelligence (AAAI) 2020, 2023, 2024, 2025

• International Symposium on Algorithmic Game Theory (SAGT) 2022, 2023, 2025

• Conference on Web and Internet Economics (WINE) 2025

Reviewing

• Conferences: CIAC, OPODIS, WALCOM, IWOCA, NETYS, PODC, DISC, WINE, SAGT, ALENEX, LATIN, ICALP, AAMAS, STACS, SODA, STOC

• Journals: Random Structures & Algorithms, AMS Mathematical Reviews, Theoretical Computer Science, Theory of Computing Systems, Mathematics of Operations Research, Information and Computation, ACM Transactions on Algorithms, SIAM Journal on Computing

Organizing team

• Conferences: SAGT 2016, MFCS 2018

Teaching Assistant at the University of Liverpool for the following courses:

• COMP108: Data Structures and Algorithms  (Spring '17-'18)

• COMP109: Foundations of Computer Science  (Fall '17-'18)

• COMP202: Complexity of Algorithms  (Spring '16-'17, '17-'18, '18-'19)

• COMP219: Advanced Artificial Intelligence  (Fall '18-'19)

• COMP281: Principles of C and Memory Management  (Spring '16-'17)

• COMP323: Introduction to Computational Game Theory  (Fall '16-'17, '17-'18, '18-'19)

Instructor at the University of Liverpool for the course:

• COMP323: Introduction to Computational Game Theory  (Fall '19-'20)

Teaching Assistant at TU Munich for the course:

• MA5226: Special Topics in Algorithmic Game Theory  (Fall '20-'21)

Co-organizer at TU Munich for the seminars:

• Complexity of Total Search Problems  (Spring '20-'21)

• Fair Division: Algorithms, Complexity & Optimization  (Fall '21-'22)

Module Supervisor at the University of Essex for the following courses:

• CE903: Group Project  (Spring '23-'24)

• CF962: Quantitative Methods in Finance and Trading  (Autumn '22-'23, '24-'25)

• CF963: Computational Models in Economics and Finance (Spring '24-'25)

• CF966: Financial Engineering and Risk Management  (Spring '22-'23, '23-'24)

• Address: Office 5A.544, School of CSEE, Colchester campus, CO4 3SQ

• Email: themistoklis dot melissourgos at essex dot ac dot uk