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Symplectic projection in generalized Dirac dynamics

Tatiana Salnikova and Eugene Kugushev

Vol. 14 (2026), No. 1, 59–70
Abstract

To describe the dynamics of Hamiltonian systems with differential constraints, a Hamiltonian vector field is projected onto the tangent planes of a distribution using a symplectic structure to obtain a vector field whose phase flow preserves distributions.

The possibility of implementing symplectic projection in degenerate cases is considered when the restriction of the symplectic structure to the tangent planes of a distribution is a degenerate 2-form. An application is presented for studying the systems with one nonintegrable constraint of general form.

The method of symplectic projection is described in the framework of Dirac structures.

Keywords
symplectic projection, nonholonomic point, almost-Dirac structure
Mathematical Subject Classification
Primary: 37J60, 70H05, 70H45
Milestones
Received: 4 August 2025
Revised: 30 September 2025
Accepted: 7 November 2025
Published: 28 November 2025

Communicated by Francesco dell'Isola
Authors
Tatiana Salnikova
MSU, Faculty of Mechanics and Mathematics
Lomonosov Moscow State University
Moscow 119991
Russia
Eugene Kugushev
MSU, Faculty of Mechanics and Mathematics
Lomonosov Moscow State University
Moscow 119991
Russia