"Singular lagrangians: some geometric structures along the Legendre
map"

New geometric structures that relate the lagrangian and hamiltonian 
formalisms defined upon a singular lagrangian are presented.  Several 
vector fields are constructed in velocity space that give new and 
precise answers to several topics like the projectability of a vector 
field to a hamiltonian vector field, the computation of the kernel 
of the presymplectic form of lagrangian formalism, the construction 
of the lagrangian dynamical vector fields, and the characterisation 
of dynamical symmetries.