Moving Frames: Difference and Differential-Difference Lagrangians

This paper develops moving frame theory for partial difference equations and for differential-difference equations with one continuous independent variable. In each case, the theory is applied to the invariant calculus of variations and the equivariant formulation of the conservation laws arising fr...

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Bibliographic Details
Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2024
Main Authors: White, Lewis C., Hydon, Peter E.
Format: Article
Language:English
Published: Інститут математики НАН України 2024
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/212117
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Moving Frames: Difference and Differential-Difference Lagrangians. Lewis C. White and Peter E. Hydon. SIGMA 20 (2024), 006, 29 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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Summary:This paper develops moving frame theory for partial difference equations and for differential-difference equations with one continuous independent variable. In each case, the theory is applied to the invariant calculus of variations and the equivariant formulation of the conservation laws arising from Noether's theorem. The differential-difference theory is not merely an amalgam of the differential and difference theories, but has additional features that reflect the need for the group action to preserve the prolongation structure. Projectable moving frames are introduced; these cause the invariant derivative operator to commute with shifts in the discrete variables. Examples include a Toda-type equation and a method of lines semi-discretization of the nonlinear Schrödinger equation.
ISSN:1815-0659