A construction of commuting systems of integrable symplectic birational maps. Lie-Poisson case

TL;DR

This paper constructs integrable symplectic birational maps from Lie-Poisson Hamiltonian systems using a discretization scheme, demonstrating their complete integrability and commuting properties, extending previous results to non-constant symplectic structures.

Contribution

It introduces a method to create integrable birational maps from Lie-Poisson systems with quadratic Hamiltonians, showing their symplectic structure and integrals of motion are preserved under discretization.

Findings

The constructed maps are symplectic perturbations of the original structure.

They possess $n$ independent integrals in involution.

Discretized commuting vector fields share the invariant structure.

Abstract

We give a construction of completely integrable ($2n$)-dimensional Hamiltonian systems with symplectic brackets of the Lie-Poisson type (linear in coordinates) and with quadratic Hamilton functions. Applying to any such system the so called Kahan-Hirota-Kimura discretization scheme, we arrive at a birational ($2n$)-dimensional map. We show that this map is symplectic with respect to a symplectic structure that is a perturbation of the original symplectic structure on $\mathbb R^{2n}$, and possesses $n$ independent integrals of motion, which are perturbations of the original Hamilton functions and are in involution with respect to the invariant symplectic structure. Thus, this map is completely integrable in the Liouville-Arnold sense. Moreover, under a suitable normalization of the original $n$-tuples of commuting vector fields, their Kahan-Hirota-Kimura discretizations also commute and share the invariant symplectic structure and the $n$ integrals of motion. This paper extends our previous ones, arXiv:1606.08238 [nlin.SI] and arXiv:1607.07085 [nlin.SI], where similar results were obtained for Hamiltonian systems with a constant (canonical) symplectic structure and cubic Hamilton functions.