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A Poisson structure on a smooth manifold is a Lie bracket (called a Poisson bracket in this special case) on the algebra . Said in another manner, it is a Lie-algebra structure on the vector space of smooth functions on such that is a vector field for each smooth function , which we call the Hamiltonian vector field associated to . These vector fields span a completely integrable singular foliation, each of whose maximal integral sub-manifolds inherits a symplectic structure. One may thus informally view a Poisson structure on a smooth manifold as a smooth partition of the ambient manifold into even-dimensional symplectic leaves, which are not necessarily of the same dimension. Poisson structures are one instance of Jacobi structures, introduced by André Lichnerowicz in 1977.〔 〕 They were further studied in the classical paper of Alan Weinstein,〔 〕 where many basic structure theorems were first proved, and which exerted a huge influence on the development of Poisson geometry — which today is deeply entangled with non-commutative geometry, integrable systems, topological field theories and representation theory, to name a few. ==Definition== Let be a smooth manifold. Let -bilinear map :. * Jacobi identity: . * Leibniz's Rule: . The first two conditions ensure that defines a Lie-algebra structure on , the adjoint is a derivation of the commutative product on . It follows that the bracket of functions and is of the form , where is a smooth bi-vector field. Conversely, given any smooth bi-vector field on , the formula defines a bilinear skew-symmetric bracket that automatically obeys Leibniz's rule. The condition that the ensuing be a Poisson bracket — i.e., satisfy the Jacobi identity — can be characterized by the non-linear partial differential equation , where : denotes the Schouten–Nijenhuis bracket on multi-vector fields. It is customary and convenient to switch between the bracket and the bi-vector points of view, and we shall do so below. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Poisson manifold」の詳細全文を読む スポンサード リンク
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