A mistake was found in the reasoning leading to a Lagrangian which we considered as equivalent from the formula for the action S(γ) below the classical mechanical problem (3) on "Non singular Hamiltonian systems and geodesic flows on surfaces with negative curvature", page 271.
@article{urn:eudml:doc:41603, title = {Erratum for "Non singular Hamiltonian systems and geodesic flows on surfaces with negative curvature".}, journal = {Publicacions Matem\`atiques}, volume = {44}, year = {2000}, pages = {355-357}, mrnumber = {MR1775771}, zbl = {0997.37025}, language = {en}, url = {http://dml.mathdoc.fr/item/urn:eudml:doc:41603} }
Lacomba, Ernesto A.; Reyes, J. Guadalupe. Erratum for "Non singular Hamiltonian systems and geodesic flows on surfaces with negative curvature".. Publicacions Matemàtiques, Tome 44 (2000) pp. 355-357. http://gdmltest.u-ga.fr/item/urn:eudml:doc:41603/