Coefficients of prolongations for symmetries of ODEs

Sophus Lie developed a systematic way to solve ODEs. He found that transformations which form a continuous group and leave a differential equation invariant can be used to simplify the equation. Lie's method uses the infinitesimal generator of these point transformations. These are symmetries o...

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Main Authors: Ricardo Alfaro, Jim Schaeferle
Format: Article
Language:English
Published: Wiley 2004-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/S016117120430904X
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author Ricardo Alfaro
Jim Schaeferle
author_facet Ricardo Alfaro
Jim Schaeferle
author_sort Ricardo Alfaro
collection DOAJ
description Sophus Lie developed a systematic way to solve ODEs. He found that transformations which form a continuous group and leave a differential equation invariant can be used to simplify the equation. Lie's method uses the infinitesimal generator of these point transformations. These are symmetries of the equation mapping solutions into solutions. Lie's methods did not find widespread use in part because the calculations for the infinitesimals were quite lengthy, needing to calculate the prolongations of the infinitesimal generator. Nowadays, prolongations are obtained using Maple or Mathematica, and Lie's theory has come back to the attention of researchers. In general, the computation of the coefficients of the (n)-prolongation is done using recursion formulas. Others have given methods that do not require recursion but use Fréchet derivatives. In this paper, we present a combinatorial approach to explicitly write the coefficients of the prolongations. Besides being novel, this approach was found to be useful by the authors for didactical and combinatorial purposes, as we show in the examples.
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spelling doaj-art-88474704d2d049e899a49aebeb2a0bb52025-02-03T01:23:48ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04252004-01-012004512741275310.1155/S016117120430904XCoefficients of prolongations for symmetries of ODEsRicardo Alfaro0Jim Schaeferle1Department of Mathematics, University of Michigan-Flint, Flint 48502, MI, USADepartment of Mathematics, University of Michigan-Flint, Flint 48502, MI, USASophus Lie developed a systematic way to solve ODEs. He found that transformations which form a continuous group and leave a differential equation invariant can be used to simplify the equation. Lie's method uses the infinitesimal generator of these point transformations. These are symmetries of the equation mapping solutions into solutions. Lie's methods did not find widespread use in part because the calculations for the infinitesimals were quite lengthy, needing to calculate the prolongations of the infinitesimal generator. Nowadays, prolongations are obtained using Maple or Mathematica, and Lie's theory has come back to the attention of researchers. In general, the computation of the coefficients of the (n)-prolongation is done using recursion formulas. Others have given methods that do not require recursion but use Fréchet derivatives. In this paper, we present a combinatorial approach to explicitly write the coefficients of the prolongations. Besides being novel, this approach was found to be useful by the authors for didactical and combinatorial purposes, as we show in the examples.http://dx.doi.org/10.1155/S016117120430904X
spellingShingle Ricardo Alfaro
Jim Schaeferle
Coefficients of prolongations for symmetries of ODEs
International Journal of Mathematics and Mathematical Sciences
title Coefficients of prolongations for symmetries of ODEs
title_full Coefficients of prolongations for symmetries of ODEs
title_fullStr Coefficients of prolongations for symmetries of ODEs
title_full_unstemmed Coefficients of prolongations for symmetries of ODEs
title_short Coefficients of prolongations for symmetries of ODEs
title_sort coefficients of prolongations for symmetries of odes
url http://dx.doi.org/10.1155/S016117120430904X
work_keys_str_mv AT ricardoalfaro coefficientsofprolongationsforsymmetriesofodes
AT jimschaeferle coefficientsofprolongationsforsymmetriesofodes