Non-homogeneous Hamiltonian structures for quasilinear systems

This paper aims at investigating necessary (and sufficient) conditions for quasilinear systems of first order PDEs to be Hamiltonian, with non-homogeneous operators of order 1 + 0, also with degenerate leading coefficient. As a byproduct, Tsarev’s compatibility conditions are extended to degenerate operators. Some examples are finally discussed.