Isa Vialard

I am a postdoctoral researcher at MPI-SWS, where I am part of the Foundations of Algorithmic Verification group led by Joël Ouaknine. I am currently working on weighted timed games. Before that, I did my PhD at Laboratoire Méthodes Formelles, ENS Paris Saclay, under the supervision of Philippe Schnoebelen.

Here are my resume and my PhD Thesis: Measuring well quasi-orders and complexity of verification.

Contact

You can contact me at surname[at]mpi-sws[dot]org, in french or english.

Research

My research interests lie in verification, especially of timed systems or well-structured transition systems. I am also interested in proof assistants and combinatorics on words.

News

Our FOSSACS paper The Value Problem for Weighted Timed Games with Two Clocks is Undecidable received the EATCS paper award at ETAPS 2026!

Publications

Journal articles

• S. Abriola, S. Halfon, A. Lopez, S. Schmitz, Ph. Schnoebelen, I. Vialard, Measuring well quasi-ordered finitary powersets, accepted for publication in Mathematical Structures in Computer Science.

• I. Vialard, On maximal order type of the lexicographic product, Logic journal of the IGPL, 10 pages.

• Ph. Schnoebelen and I. Vialard, On the piecewise complexity of words, Acta Informatica, vol 62 (2025), 22 pages.

• I. Vialard, On the Width of the Cartesian Product of Ordinals, Order, vol 42, pp. 37-58 (2024).

Conference proceedings

• Q. Guilmant, J. Ouaknine, I. Vialard, The Value Problem for Weighted Timed Games with Two Clocks is Undecidable, Turin, FOSSACS 2026. EATCS Best Paper Award.

• R. Aghamov, C. Baier, J. Ouaknine, J. Piribauer, M. Vahanwala, I. Vialard, Temporal Properties of Conditional Independence in Dynamic Bayesian Networks, AAAI 2026.

• I. Vialard, Deciding the Value of Two-Clock Almost Non-Zeno Weighted Timed Games, Paris, CSL 2026.

• Ph. Schnoebelen, M. Veron, I. Vialard, A Tropical Approach to the Compositional Piecewise Complexity of Words and Compressed Words, Aarhus, ICALP 2025.

• M. Praveen, Ph. Schnoebelen, I. Vialard, J. Veron, On the piecewise complexity of words and periodic words, Cochem, SOFSEM 2024.

• I. Vialard, Ordinal Measures of the Set of Finite Multisets, Bordeaux, MFCS 2023.

• M. Blondin, M. Cadilhac, B. Courchesne, L. Guillou, C. Mascle, I. Vialard, Population Protocols over Ordered Agents, London, ICALP 2026.

Presentations in conferences, workshops, seminars

• Deciding the Value of Two-Clock Almost Non-Zeno Weighted Timed Games, CSL 2026.

• Using knowledge.sty, Logic and Mentoring Workshop 2026.

• (Un)decidability of 2-clock Weighted Timed games, Séminaire Automate de l’IRIF, Séminaire MOVE du LIS, Séminaire du GT Informel au LMF, Séminaire 68NQRT de l’IRISA.

• Tropical algebra for piecewise complexity, Highlights, Saarbrucken, September 2025.

• Tropical algebra for piecewise complexity, ICALP, Aarhus, July 2025.

• Tropical algebra for piecewise complexity, workshop “Words and Subwords”, Liège, April 2025.

• Journées annuelles du GT Verif, Lille, Novembre 2024.

• Séminaire LX du LaBRI, Bordeaux, Novembre 2024.

• Séminaire automate de l’IRIF, Paris, Octobre 2024.

• My PhD defense, Measuring well quasi-orders and complexity of verification, ENS Paris-Saclay, July 2024.

• Journées annuelles du GT Verif, Paris, Novembre 2023.

• Ordinal measures of the set of finite multisets, MFCS, Bordeaux, September 2023.

• Séminaire à Liverpool University, July 2023.

• Elementary, Dr. Powerset!, workshop “WQO-BQO - what is up?”, Lyon, March 2023. (This is the sequel to a talk given by Aliaume Lopez at the same workshop.)

• Research school “Discrete mathematics and logic”, Marseille, January 2023.

• Highlights, Paris, June 2022.

Teaching and supervision

• May-August 2025: I am supervising Angel Wuttke for his internship on the topic of 2-clock almost strongly non-Zeno weighted timed games.

• February-June 2026: I am supervising Baptiste Diedler for his internship on the topic of parameterized timed automata.

• 2021-2024: I taught Formal languages, Rewriting theory, Architecture and systems, and Logic Project (an introduction to proof assistants) at ENS Paris-Saclay.

Miscellaneous

• I have a ha-index of 64.
• My favourite time-sink : Rätsel Portal