Alexandros Tsigonias-Dimitriadis

Alexandros Tsigonias-Dimitriadis

Graduate Programme Participant, European Central Bank

Hi, I’m Alexandros!

I am currently a Graduate Programme Participant at the European Central Bank. This is a selective programme for recent (PhD) graduates, that involves two one-year assignments in two business areas and submitting a research paper at the end of the programme for evaluation. My first-year allocation is in Risk Management and my second-year in Information Systems.

Before coming to the ECB, I was a postdoctoral researcher at the Department of Industrial Engineering of the University of Chile hosted by Prof. José Correa. I obtained my PhD from the Department of Mathematics of the TUM School of Computation, Information and Technology. At TU Munich, I was advised by Prof. Andreas S. Schulz and was a member of the interdisciplinary research group Advanced Optimization in a Networked Economy (AdONE) and the Operations Research Group. During my PhD and postdoc, I had the opportunity to spend some time at Google Research Zurich and the Sapienza University of Rome. I received my Diploma (BSc and MEng equivalent) in Electrical and Computer Engineering from the National Technical University of Athens, where I was advised by Prof. Dimitris Fotakis.

My research during my PhD and postdoc revolved mainly around the design of algorithms and mechanisms for fair and efficient resource allocation with applications in pricing, recommender systems, apportionment, and generally complex scenarios arising in (online) markets and platforms. To study these problems, I have used a broad set of tools from algorithms, economics, operations, mechanism design, machine learning, and optimization. During my first year at the ECB, I also started working on topics related to computational social science and central banking communication, using natural language processing and econometric methods.

I’m still trying to allocate a fraction of my time to research. This page serves mainly for posting updates related to my research papers, and keeping all the material related to them so that they can be accessed easily.

You can find a copy of my CV here (last update: August 2024).

Interests
  • Economics and Computation
  • Operations Research & Optimization
  • AI & Machine Learning
  • Computational Social Science
Education

  • PhD in Mathematics, 2022

    Technical University of Munich

  • Diploma in Electrical and Computer Engineering, 2018

    National Technical University of Athens

News

  • [September 2024] I just started the ECB Graduate Programme!

  • [June 2024] The journal version of our paper “The Secretary Problem with Independent Sampling” has been published in Management Science! You can find it here. A big thank you to my co-authors for this wonderful collaboration!

  • [September 2023] Our paper with Tomer, Stefano, Rebecca, and Matteo has been accepted to WINE 2023!

  • [July 2023] I just started a new position at the European Central Bank!

  • [May 2023] I just started a research visit at Google Zurich hosted by Paul Dütting! I will be here for two months working on exciting algorithmic questions.

  • [May 2023] Our paper on the Prophet Secretary problem with Paul, Evangelia, Rojin, and Yifeng has been accepted to EC ‘23! We will post the full paper very soon on arXiv.

  • [August 2022] I completed my PhD at TU Munich. Next, I will be moving to the University of Chile, where I will do a one-year postdoc working with Prof. José Correa and other members of the ICMD team!

  • [July 2022] Check out our new preprint on “Prophet Inequalities via the Expected Competitive Ratio”.

  • [May 2022] Our paper on robust revenue maximization has been accepted to ACM TEAC!

  • [January 2022] In March, I will visit Prof. Stefano Leonardi and his group at the Sapienza Università di Roma, as part of the COST STSM program!

  • [October 2021] I will (virtually) present our work on The Secretary Problem with Independent Sampling at the INFORMS Annual Meeting (VTA21, 26/10 at 6AM PT).

Journal Articles

Paul Dütting, Evangelia Gergatsouli, Rojin Rezvan, Yifeng Teng, Alexandros Tsigonias-Dimitriadis (2024). Prophet Secretary Against the Online Optimal. Minor revision, Mathematics of Operations Research.

José Correa, Andrés Cristi, Laurent Feuilloley, Tim Oosterwijk, Alexandros Tsigonias-Dimitriadis (2024). The Secretary Problem with Independent Sampling. Articles in Advance, Management Science.

DOI

Yiannis Giannakopoulos, Diogo Poças, Alexandros Tsigonias-Dimitriadis (2022). Robust Revenue Maximization Under Minimal Statistical Information. ACM Transactions on Economics and Computation (ACM TEAC).

Cite DOI arXiv

Conference Publications

Tomer Ezra, Stefano Leonardi, Rebecca Reiffenhäuser, Matteo Russo, Alexandros Tsigonias-Dimitriadis (2023). Prophet Inequalities via the Expected Competitive Ratio. Extended abstract in the 19th Conference on Web and Internet Economics (WINE ‘23).

arXiv slides

Paul Dütting, Evangelia Gergatsouli, Rojin Rezvan, Yifeng Teng, Alexandros Tsigonias-Dimitriadis (2023). Prophet Secretary Against the Online Optimal. In the proceedings of the 24th Conference on Economics and Computation (EC ‘23).

arXiv DOI poster

José Correa, Andrés Cristi, Laurent Feuilloley, Tim Oosterwijk, Alexandros Tsigonias-Dimitriadis (2021). The Secretary Problem with Independent Sampling. Extended abstract in the 2021 ACM-SIAM Symposium on Discrete Algorithms (SODA ‘21).

DOI arXiv slides poster

Yiannis Giannakopoulos, Diogo Poças, Alexandros Tsigonias-Dimitriadis (2020). Robust Revenue Maximization Under Minimal Statistical Information. Extended abstract in the 16th Conference on Web and Internet Economics (WINE ‘20).

DOI slides video

Working Papers

Tomer Ezra, Stefano Leonardi, Rebecca Reiffenhäuser, Matteo Russo, Alexandros Tsigonias-Dimitriadis (2024). Prophet Inequalities via the Expected Competitive Ratio. Major revision, ACM Transactions on Economics and Computation.

Javier Cembrano, José Correa, Ulrike Schmidt-Kraepelin, Alexandros Tsigonias-Dimitriadis, Victor Verdugo (2024). New Combinatorial Insights for Monotone Apportionment. Submitted.

José Correa, Émile Naquin, Nicolás Stier-Moses, Alexandros Tsigonias-Dimitriadis, Victor Verdugo (2024). Online Policies for Content Recommendation with Fairness Constraints. In preparation for submission.

Eleni Batziou, Giorgos Bouritsas, Alexandros Tsigonias-Dimitriadis (2023). Preference Elicitation in Combinatorial Domains: An Improved Approach using Reinforcement Learning. Working paper.

Teaching / Supervision

I have been a teaching assistant for the following courses:

I have co-supervised Master theses on the following topics:

  • Unified Voice or Cacophony? A Discordance Index of the European Central Bank Governing Council Members, ECB & Barcelona School of Economics
  • Iterative Combinatorial Auctions: Improved Running Time via Machine Learning, TUM
  • Experimental Evaluation of Robust Revenue-Maximizing Auctions, TUM

Contact