Jean-Philippe Lessard

Professor of Mathematics

Department of Mathematics and Statistics
McGill University, Montréal

Research areas

Infinite dimensional dynamical systems, computer-assisted proofs, partial differential equations, delay differential equations, ordinary differential equations, celestial mechanics, topological methods, fixed point methods, functional analytic methods, continuation methods, approximation theory, spectral methods, bifurcation theory, stable and unstable manifolds, chaotic dynamics, Morse–Conley–Floer homology.

Short biography

I received my Ph.D. from Georgia Tech in 2007 under the supervision of Konstantin Mischaikow, after an M.Sc. at the Université de Montréal (2002) and a B.Sc. at the Université de Sherbrooke (2000). I then held postdoctoral positions at VU University Amsterdam, Rutgers University and the Institute for Advanced Study (NSF Mathematical Sciences Institutes Postdoctoral Fellow), before leading the Computational Mathematics research line at BCAM in Bilbao. I was a professor at Université Laval from 2011 to 2017, and joined McGill University in 2017, where I have been Professor since 2022. From 2019 to 2021, I served as Deputy Director of Scientific Programs at the Centre de recherches mathématiques (CRM). I am a member of the editorial board of the Journal of Dynamics and Differential Equations.

News and Highlights

• May 3–7, 2027 CISM Advanced School Computer-Assisted Proofs in Delayed and Infinite-Dimensional Dynamical Systems, Udine, Italy, coordinated with Dimitri Breda.
• June 15–17, 2027 Minicourse From Numerical Approximations to Rigorous Proofs in Dynamical Systems at SDS2027 – Structural Dynamical Systems: Computational Aspects, Monopoli, Italy.
• Periodic orbits of state-dependent delay equations Our new preprint Computer-assisted proofs of periodic solutions of state-dependent delay equations beyond perturbative regimes (with J.B. van den Berg, M. Breden, M. Cadiot and K. Church) gives, to our knowledge, the first computer-assisted proofs of existence of periodic solutions of state-dependent delay equations outside perturbative regimes, where the time lag is determined by the state of the system itself. The examples include a threshold-type delay model of operon dynamics in gene regulation. More on this research →
• A proof of Marchal’s conjecture Our paper From the Lagrange Triangle to the Figure Eight Choreography: Proof of Marchal’s Conjecture (with R. Calleja, C. García-Azpeitia, O. Hénot and J.D. Mireles James) has been accepted for publication in the Transactions of the American Mathematical Society. It gives a computer-assisted proof of Marchal’s conjecture on the family of periodic orbits connecting Lagrange’s equilateral triangle to the figure-eight choreography of the three-body problem. More on this research →

Online profiles and CV

Google Scholar ResearchGate ORCID Curriculum Vitae (PDF)

Recent work

1. [85]
   Computer-assisted proofs of periodic solutions of state-dependent delay equations beyond perturbative regimes Preprint

   J.B. van den Berg, M. Breden, M. Cadiot, K. Church and J.-P. Lessard

   Preprint, 2026

   arXiv:2610.36216 Codes on GitHub
2. [84]
   Rigorous integration of semilinear parabolic PDEs: forward evolution bounds and projected boundary value problems Preprint

   J.-P. Lessard and A. Takayasu

   Preprint, 2026

   arXiv:2610.29871 Codes on GitHub
3. [83]
   Rigorous verification of period-doubling bifurcations in maps Preprint

   O. Hénot and J.-P. Lessard

   Preprint, 2026

   arXiv:2610.22986 Codes on GitHub
4. [82]
   Platonic constellations of periodic motions in the (n+1)- body problem Preprint

   K. Constantineau, C. García-Azpeitia and J.-P. Lessard

   Preprint, 2026

   arXiv:2609.10242 Codes on GitHub
5. [81]
   Rigorous Validation of Cusp Bifurcations of Stationary Periodic Patterns in Partial Differential Equations Preprint

   D. Blanco and J.-P. Lessard

   Preprint, 2026

   arXiv:2608.15613 Codes on GitHub

All publications →

This page was last updated on October 29, 2026.