Symplectic linearization of singular Lagrangian foliations in \(M^{4}\). (Q1405256)

While studying the classification of the symplectic structures on a 4-dimensional manifold \(M^{4}\), the authors show that the singular Lagrangian foliation associated to an integrable Hamiltonian system with two degrees of freedom, near a non-degenerate singular orbit, is symplectically equivalent to the linearized foliation.