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arXiv · 1811.01855

A variational perspective on continuum limits of ABS and lattice GD equations

Mats Vermeeren
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Abstract

A pluri-Lagrangian structure is an attribute of integrability for lattice equations and for hierarchies of differential equations. It combines the notion of multi-dimensional consistency (in the discrete case) or commutativity of the flows (in the continuous case) with a variational principle. Recently we developed a continuum limit procedure for pluri-Lagrangian systems, which we now apply to most of the ABS list and some members of the lattice Gelfand-Dickey hierarchy. We obtain pluri-Lagrangian structures for many hierarchies of integrable PDEs for which such structures where previously unknown. This includes the Krichever-Novikov hierarchy, the double hierarchy of sine-Gordon and modified KdV equations, and a first example of a continuous multi-component pluri-Lagrangian system.

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Mats Vermeeren. 2018-11-05. A variational perspective on continuum limits of ABS and lattice GD equations. https://doi.org/10.3842/sigma.2019.044

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