Adjoint methods for obstacle problems and weakly coupled systems of PDE
  The adjoint method, recently introduced by Evans, is used to study obstacle problems, weakly coupled systems, cell problems for weakly coupled systems of Hamilton-Jacobi equations, and weakly coupled systems of obstacle type. In particular, new results about the speed of convergence of common approximation procedures are derived. 
Filippo Cagnetti, Diogo Gomes, and Hung Tran
math.AP