Julien Codsi

ABOUT ME

Since 2023, I have been a PhD student in applied and computational mathematics at Princeton University under the supervision of Maria Chudnovsky. My research focuses mainly on structural graph theory, with a secondary interest in quantum computing.

Previously, I worked in quantum computing under the supervision of Gilles Brassard at Université de Montréal, before shifting to graph theory (I earned a Master's degree in passing).

I also completed a Master’s degree at Oxford University with John van de Wetering, focused on simulating quantum circuits using graph-theoretic tools via the ZX calculus.

I also completed a Bachelor's degree in mathématique et informatique at Université de Montréal.

Email Resume CV LinkedIn

RESEARCH

Here are some projects I have worked on.

Tree-independence number and forbidden induced subgraphs: excluding a vertex path and a biclique (with M. Chudnovsky, J.P. Gollin, M. Milanič and V. Sivashankar) 2026.	Preprint
Induced Minors and Coarse Tree Decompositions (with M. Chudnovsky, Ajaykrishnan E S and D. Lokshtanov) 2026.	Preprint
Unifying Graph Measures and Stabilizer Decompositions for the Classical Simulation of Quantum Circuits (with T. Laakkonen) 2026.	Preprint
Extremal Graphs for the Lights Out Problem (with S. Cristancho, A. Divoux and V. Sivashankar) 2026.	Preprint
Counting independent sets in structured graphs (with M. Bucić and M. Chudnovsky) Combinatorics, Probability and Computing, 34(5):625-634, 2025.	Publication
Induced minors and subpolynomial treewidth (with M. Chudnovsky, D. Fischer and D. Lokshtanov) 2025.	Preprint
Localized Erdős-Pósa Property for Subdivisions (with I.S. Ai and M. Chudnovsky) 2025.	Preprint
Tree-independence number VI. Thetas and pyramids (with M. Chudnovsky) 2025.	Preprint
Induced subgraphs and tree decompositions XIX. Thetas and forests (with M. Chudnovsky, S. Hajebi and S. Spirkl) 2025.	Preprint
Tree independence number V. Walls and claws (with M. Chudnovsky, D. Lokshtanov, M. Milanič and V. Sivashankar) 2025.	Preprint
LinA: a faster approach to piecewise linear approximations using corridors and its application to mixed-integer optimization (with S.U. Ngueveu and B. Gendron) Mathematical Programming Computation, 17(2):265-306, 2025. Code complement	Publication
Classically simulating intermediate-scale instantaneous quantum polynomial circuits through a random graph approach (with J. van de Wetering) Physical Review A, 111(1):012422, 2025.	Publication
Cutting-edge graphical stabiliser decompositions for classical simulation of quantum circuits Master's thesis, University of Oxford, 2022.	Thesis
A case study in learning in metagames: Super Smash Bros. Melee (with A. Vetta) Proceedings of the AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment, 2021.	Publication