%0 Journal Article %A Muñoz Masqué, Jaime %A Pozo Coronado, Luis Miguel %T Parameter-invariant second-order variational problems in one variable %D 1998 %@ 0305-4470 %U https://hdl.handle.net/20.500.14352/57772 %X A projection is defined such that a second-order Lagrangian density factors through this projection module contact forms if and only if it is parameter invariant. In this way, a geometric interpretation of the parameter invariance conditions is obtained. The above projection is then used to prove the strict factorization of the Poincare-Cartan form attached to a parameter-invariant variational problem thus leading us to state the Hamilton-Cartan formalism, the complete description of symmetries and regularity for such problems. The case of the squared curvature Lagrangian in the plane is analysed especially. %~