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Dirac brackets in constrained dynamics. (English) Zbl 0956.37049
Summary: An unified geometric description of various Dirac brackets for regular and singular Lagrangians with holonomic or non-holonomic constraints is presented. Such an unified picture relies only on two simple physical arguments: “classical complementarity principle” and “principle of deterministic evolution”. The appropriate geometrization of these principles allows to construct a recursive constraint algorithm that eventually produces a maximal final state manifold where a well defined dynamics exists, naturally equipped with a Dirac bracket such that the dynamics is Hamiltonian with respect to it. A classification of constraints in first and second class as envisaged by Dirac emerges also naturally from this picture. The Dirac brackets constructed show explicitly the existence of classical anomalies for such Lagrangian theories since in general they do not verify Jacobi’s identity. Such features are discussed using a variety of examples.

MSC:
 37J60 Nonholonomic dynamical systems 53D17 Poisson manifolds; Poisson groupoids and algebroids 70F25 Nonholonomic systems related to the dynamics of a system of particles 70H03 Lagrange’s equations 70H45 Constrained dynamics, Dirac’s theory of constraints
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