Hamiltonian Structure of PI Hierarchy

Abstract

The string equation of type $(2,2g+1)$ may be thought of as a higher order analogue of the first Painlevé equation that corresponds to the case of $g=1$. For $g>1$, this equation is accompanied with a finite set of commuting isomonodromic deformations, and they altogether form a hierarchy called the PI hierarchy. This hierarchy gives an isomonodromic analogue of the well known Mumford system. The Hamiltonian structure of the Lax equations can be formulated by the same Poisson structure as the Mumford system. A set of Darboux coordinates, which have been used for the Mumford system, can be introduced in this hierarchy as well. The equations of motion in these Darboux coordinates turn out to take a Hamiltonian form, but the Hamiltonians are different from the Hamiltonians of the Lax equations (except for the lowest one that corresponds to the string equation itself).

This is a contribution to the Vadim Kuznetsov Memorial Issue on Integrable Systems and Related Topics, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/

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Cited by in corpus (4)

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• Solutions of the Painleve VI Equation from Reduction of Integrable Hierarchy in a Grassmannian Approach
• Systematic construction of non-autonomous Hamiltonian equations of Painlevé-type. I. Frobenius integrability
• Asymptotic Properties of a Special Solution to the (3,4) String Equation