On an order reduction theorem in the Lagrangian formalism

D. R. Grigore
1996 Il Nuovo Cimento B  
We provide a new proof of a important theorem in the Lagrangian formalism about necessary and sufficient conditions for a second-order variational system of equations to follow from a first-order Lagrangian.
doi:10.1007/bf02741483 fatcat:oueiyepgz5cuvlv7shbjaxed4e