Commuting Hamiltonians and multi-time Hamilton-Jacobi equations
  We prove that if a sequence of pairs of smooth commuting Hamiltonians converge in the $C^0$ topology to a pair of smooth Hamiltonians, these commute. This allows us define the notion of commuting continuous Hamiltonians. As an application we extend some results of Barles and Tourin on multi-time Hamilton-Jacobi equations to a more general setting. 
Franco Cardin, Claude Viterbo (CMLS-EcolePolytechnique)