Hamiltonian G-Actions and the Marsden-Weinstein-Meyer Reduction
摘要
In this chapter, which aims to set a convenient framework for the study of the class of Hamiltonian systems with symmetries, the definition of Hamiltonian G-action and of moment map will be introduced. The former provides a geometrical model for the notion of symmetry in Hamiltonian mechanics, the latter is a broad generalization of the concepts of linear and angular momenta, and it provides a geometrical setting where the symmetries become an efficient a tool to solve the Hamilton equations. In particular, as it will be emphasized hereafter, the moment map is the main ingredient in the theory of the Hamiltonian reduction which, besides its applications to dynamics, is one of the more, if not the most, efficient tool to produce new symplectic manifolds from old ones.