I am third-year PhD student in the Institute of Machine Learning at ETH Zürich. I am a member of Rycolab, and I am co-advised by Ryan Cotterell (ETH Zürich) and David Chiang (University of Notre Dame). Prior to my PhD, I obtained a bachelor's degree in Software Engineering from The University of Sheffield, UK, and a master's degree in Data Science from ETH Zürich. I did a research internship in NLP at IBM Research in Zürich during my master's degree. Here is a more or less updated resume.
My current research mostly focuses on understanding the capabilities of neural language models using formal language theory. However, I'm always interested in fun bits of formal language theory.

News

I presented the paper Training Neural Networks as Recognizers of Formal Languages at FlaNN.

I presented with Brian DuSell the paper Training Neural Networks as Recognizers of Formal Languages in Michael Hanh's group at Saarland University.

The paper Training Neural Networks as Recognizers of Formal Languages, written together with Ghazal Khalighinejad, Anej Svete, Josef Valvoda, Ryan Cotterell, and Brian DuSell, was accepted at ICLR 2025.

I presented with Anej Svete the paper On the Representational Capacity of Neural Language Models with Chain-of-Thought Reasoning at ACL 2024. I also gave the tutorial Computational Expressivity of Neural Language Models, together with Robin Chan, Ryan Cotterell, William Merrill, Franz Nowak, Clemente Pasti, Lena Strobl, and Anej Svete at ACL 2024.

Publications

Training Neural Networks as Recognizers of Formal Languages

Alexandra Butoi, Ghazal Khalighinejad, Anej Svete, Josef Valvoda, Ryan Cotterell, and Brian DuSell

In The Thirteenth International Conference on Learning Representations, Singapore, April 2025

On the Representational Capacity of Neural Language Models with Chain-of-Thought Reasoning

Franz Nowak, Anej Svete, Alexandra Butoi, and Ryan Cotterell

In Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics, Bangkok, Thailand, August 2024

Efficient Algorithms for Recognizing Weighted Tree-Adjoining Languages

Alexandra Butoi, Tim Vieira, Ryan Cotterell, and David Chiang

In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, Singapore, December 2023

Convergence and Diversity in the Control Hierarchy

Alexandra Butoi, Ryan Cotterell, and David Chiang

In Proceedings of the 61nd Annual Meeting of the Association for Computational Linguistics, Toronto, Canada, July 2023

Algorithms for Weighted Pushdown Automata

Alexandra Butoi, Brian DuSell, Tim Vieira, Ryan Cotterell, and David Chiang

In Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing, Abu Dhabi, United Arab Emirates, December 2022

Teaching

I gave a few courses on the expressivity of neural language models at conferences and summer schools:

Computational Expressivity of Neural Language Models, ACL 2024

Tutorial, Bangkok, Thailand, August 2024

Formal Language Theory and Neural Networks, ESSLLI 2023

Course, Ljubljana, Slovenia, July-August 2023

Additionally, I've been a teaching assistant for the following courses at ETH Zürich:

263-5352-00L Advanced Formal Language Theory, ETH Zürich

Head Teaching Assistant, Spring 2024, 2025

252-3005-00L Natural Language Processing, ETH Zürich

Teaching Assistant, Spring 2021, Autumn 2022, 2023, 2024

263-5352-00L Advanced Formal Language Theory, ETH Zürich

Teaching Assistant, Spring 2022, 2023