In this paper we discuss singular Lagrangian systems on the framework of contact geometry. These systems exhibit a dissipative behavior in contrast with the symplectic scenario. We develop a constraint algorithm similar to the presymplectic one studied by Gotay and Nester (the geometrization of the well-known Dirac-Bergman algorithm). We also construct the Hamiltonian counterpart and prove the equivalence with the Lagrangian side. A Dirac-Jacobi bracket is constructed similar to the Dirac bracket.
@article{arxiv.1904.11429,
title = {Singular Lagrangians and precontact Hamiltonian Systems},
author = {Manuel de León and Manuel Lainz Valcázar},
journal= {arXiv preprint arXiv:1904.11429},
year = {2019}
}