Notorious software bugs, such as that of the first Ariane 5 flight in 1996, have revealed the shortcomings of the standard tests used in complex systems. Created in 2003, the "Complex Systems Engineering" Chair has led to major theoretical and practical advances in the modeling, optimization and validation of complex systems across an array of fields, including critical control systems in the aeronautics and space industries. The research conducted by the Chair also focuses on control systems in networks, and cyber-physical systems. It is supported by l’X, its Foundation, ENSTA ParisTech, Télécom ParisTech, Dassault Aviation, DCNS Research, the French Directorate General of Armaments (DGA) and Thales.