The Bi-Hamiltonian Structure of the Short Pulse Equation

We prove the integrability of the short pulse equation derived recently by Sch"afer and Wayne from a hamiltonian point of view. We give its bi-hamiltonian structure and show how the recursion operator defined by the hamiltonian operators is connected with the one obtained by Sakovich and Sakovich. An alternative zero-curvature formulation is also given.