Guy Barles is a former professor at the University of Tours (1990-2021). During his career, his main research theme was nonlinear elliptic and parabolic equations, and in particular Hamilton-Jacobi and nonlocal equations. His main contributions concern various asymptotic problems including Large Deviations, homogenization and rate of convergence for numerical schemes, as well as front propagation problems, optimal control and modelling. He is the author of more than 120 articles, proceedings and books, including an introduction in French to viscosity solutions for Hamilton-Jacobi Equations and deterministic control problems.Emmanuel Chasseigne is Maître de Conférences at the University of Tours since 2001. His main research themes are nonlinear elliptic and parabolic equations, diffusion equations, Hamilton-Jacobi and nonlocal equations. His main contributions are related to qualitative properties of solutions, optimal initial data, asymptotic problems, and optimal control, representing a total of 40 articles.

• General Introduction.- Basic Continuous Framework and Classical Assumptions Revisited.- Part I: A Toolbox for Discontinuous Hamilton-Jacobi Equations and Control Problems.- PDE Tools.- Control Tools.- Mixed Tools.- Other Tools.- Part II: Deterministic Control Problems and Hamilton-Jacobi Equations for Codimension One Discontinuities.- Introduction: Ishii Solutions for the Hyperplane Case.- The Control Problem and the "Natural" Value Function.- A Less Natural Value-Function, Regular and Singular Dynamics.- Uniqueness and Non-Uniqueness Features.- Adding a Specific Problem on the Interface.- Remarks on the Uniqueness Proofs, Problems without Controllability.- Further Discussions and Open Problems.- Part III: Hamilton-Jacobi Equations with Codimension One Discontinuities: The "Network" Point of View.- Introduction.- Flux-Limited Solutions for Control Problems and Quasi-Convex Hamiltonians.- Junction Viscosity Solutions.- From One Notion of Solution to the Others.- Applications and Emblematic Examples.- Further Discussions and Open Problems.- Part IV: General Discontinuities: Stratified Problems.- Stratified Solutions.- Connections with Control Problems and Ishii Solutions.- Stability Results.- Applications.- Further Discussions and Open Problems.- Part V: State-Constraint Problems.- Introduction to State-Constraint Problems.- Stratified Solutions for State-Constraint Problems.- Classical Boundary Conditions and Stratified Formulation.- Stability for Singular Boundary Value Problems.- Further Discussions and Open Problems.- Part VI: Investigating Other Applications.- KPP-Type Problems with Discontinuities.- And What about Jumps? And What about Networks.- Further Discussions and Open Problems.- Part VII: Appendices.- Notations and Terminology.- Assumptions, Hypotheses, Notions of Solutions.

“The monograph provides comprehensive, long, and self-contained descriptions and analyses of such problems and can be used for a one semester course at the graduate or advanced undergraduate level.” (Giuseppe Maria Coclite, Mathematical Reviews, June, 2025)