Construction of Lagrangian and Hamiltonian Structures starting from one   Constant of Motion
  The problem of the construction of Lagrangian and Hamiltonian structures starting from two first order equations of motion is presented. This new approach requires the knowledge of one (time independent) constant of motion for the dynamical system only. The Hamiltonian and Lagrangian structures are constructed, the Hamilton Jacobi equation is then written and solved and the second (time dependent) constant of the motion for the problem is explicitly exhibited. 
Sergio A. Hojman
physics.class-ph