Authors: F. Pugliese, A. M. Vinogradov

A general geometric method for studying mechanical systems whose phase space may undergo an abrupt reduction is proposed. This method is based on a variant of the Transition Principle, proposed for the first time in Appendix II of paper by Vinogradov, A.M., Kupershmidt, B.A., The Structures of Hamiltonian Mechanics, Russ. Math.Surv. 2 (1977) for elastic collisions.

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