Aubry-Mather theory and periodic solutions of the forced burgers equation

Consider a Hamiltonian system with Hamiltonian of the form H (cursive Greek chi, t, p) where H is convex in p and periodic in cursive Greek chi, and t and cursive Greek chi ∈ double-struck R sign¹. It is well-known that its smooth invariant curves correspond to smooth Z²-periodic solutions of the PDE u_t + H (cursive Greek chi, t, u)_{cursive Greek chi} =0. In this paper, we establish a connection between the Aubry-Mather theory of invariant sets of the Hamiltonian system and Z²-periodic weak solutions of this PDE by realizing the Aubry-Mather sets as closed subsets of the graphs of these weak solutions. We show that the complement of the Aubry-Mather set on the graph can be viewed as a subset of the generalized unstable manifold of the Aubry-Mather set, defined in (2.24). The graph itself is a backward-invariant set of the Hamiltonian system. The basic idea is to embed the globally minimizing orbits used in the Aubry-Mather theory into the characteristic fields of the above PDE. This is done by making use of one- and two-sided minimizers, a notion introduced in [12] and inspired by the work of Morse on geodesics of type A [26], The asymptotic slope of the minimizers, also known as the rotation number, is given by the derivative of the homogenized Hamiltonian, defined in [21]. As an application, we prove that the Z²-periodic weak solution of the above PDE with given irrational asymptotic slope is unique. A similar connection also exists in multidimensional problems with the convex Hamiltonian, except that in higher dimensions, two-sided minimizers with a specified asymptotic slope may not exist.