Abstract
When Lie developed symmetry analysis, he took the equations to be defined in the complex domain but did not explicitly use the entailed complex analyticity. Making it explicit necessitates the incorporation of the Cauchy–Riemann equations into the original system of equations, which modifies the symmetries of the system. This point was followed up by us, and some of our students, in a series of papers (and theses). It was found that complex methods, when they are applicable, provide more powerful tools for obtaining solutions and integrals of differential equations, even enabling us to find solutions of systems of differential equations that possess no symmetries. In this chapter we review the methods developed and then pose the crucial question that was begged in saying “when they are applicable.” When would they be applicable and why, or how, does the complex method work? We indicate some lines to pursue to try to find the answers, or at least partial answers, to these questions.
Dedicated to the memory of one of the most innovative workers in the field of Symmetry Analysis, after Sophus Lie, Nail Hairullovich Ibragimov, who initiated many new methods for using Lie Analysis to deal with differential equations.
FM is Visiting Professor at UNSW for 2020.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Lie S (1967) Differential equations. Chelsea, New York
Lie S (1883) Klassification und integration von gewönlichen differentialgleichungen zwischen x, y, die eine gruppe von transformationen gestaten. Arch Math
Lie S (1891) Lectures on differential equations with known infinitesimal transformations. Leipzig, Teubner (in German, Lie’s lectures by Sheffers G)
Lie S (1893) Theorie der Transformationsgruppen. III. Teubner, Leipzig
Ibragimov NH (1999) Elementary Lie group analysis and ordinary differential equations. Wiley, Chichester
Stephani H (1996) Differential equations: their solutions using symmetries. Cambridge University Press, Cambridge
Tressé A (1894) Sur les invariants differentiels des groupes continus de transformations. Acta Math 18:1
Chern SS (1937) Sur la geometrie d’une equation differentielle du troiseme orde. CR Acad Sci Paris, 1227; (1940) The geometry of the differential equation \(y^{\prime \prime \prime } = F(x,y,y^{\prime },y^{\prime \prime })\). Sci Rep Nat Tsing Hua Univ. 4, 97
Mahomed FM, Leach PGL (1990) Symmetry Lie algebra of nth. order ordinary differential equations. J Math Anal Appl 151:80
Grebot G (1997) The linearization of third order ODEs; the characterization of third order ordinary differential equations admitting a transitive fibre-preserving point symmetry group. J Math Anal Appl 206:364
Wafo Soh C, Mahomed FM (2001) Linearization criteria for a system of second-order ordinary differential equations. Int J Nonlinear Mech 36:671
Gorringe VM, Leach PGL (1988) Lie point symmetries for systems of \(2\)nd order linear ordinary differential equations. Quaestiones Mathematicae 11:95
Wafo Soh C, Mahomed FM (2000) Symmetry Breaking for a System of Two Linear Second-Order Ordinary Differential Equation. Nonlinear Dyn 22:121
Qadir A (2020) Einstein’s general theory of relativity. Cambridge Scholars Publishers, Cambridge
Aminova AV, Aminov NA-M (2000) Projective geometry of systems of differential equations: general conception. Tensor N S 62:65; (2006) Projective geometry of systems of second-order differential equations. Sbornik: Math 197:951
Feroze T, Mahomed FM, Qadir A (2006) The connection between isometries and symmetries of geodesic equations of the underlying spaces. Nonlinear Dyn 45:65
Mahomed FM, Qadir A (2007) Linearization criteria for a system of second order quadratically semi-linear ordinary differential equations. Nonlinear Dyn 48:417
Bokhari AH, Qadir A (1985) A prescription for \(n\)-dimensional vierbeins. ZAMP 36:184
Mahomed FM, Qadir A (2009) Invariant linearization criteria for systems of cubically semi-linear second order ordinary differential equations. J Nonlin Math Phys 16:1
Fredericks E, Mahomed FM, Momonia E, Qadir A (2008) Constructing a space from the system of geodesic equations. Comp Phys Commun 179:438
Ali S (2009) Complex symmetry analysis. PhD thesis, NUST CAMP
Ali S, Mahomed FM, Qadir A (2009) Complex Lie symmetries for scalar second-order ordinary differential equations. Nonlinear Anal: Real World App 10:3335
Safdar M (2003) Solvability of differential equations by complex symmetry analysis. PhD Thesis, NUST CAMP
Safdar M, Qadir A, Ali S (2011) Inequivalence of classes of linearizable systems of cubically semi linear ordinary differential equations obtained by real and complex symmetry analysis. Math Comp Appl 16:923
Safdar M, Qadir A, Ali S (2011) Linearizability of systems of ordinary differential equations obtained by complex symmetry analysis. Math Problems Eng 2011:171834
Ali S, Safdar M, Qadir A (2014) Linearization from complex Lie point transformations. J Appl Math 2014:793247
Dutt HM, Safdar M (2015) Linearization of two-dimensional complex linearizable system of second order ordinary differential equations. Appl Math Sci 9:2889
Noether E (1918) Invariante Variationsprobleme Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen. Mathematisch-Physikalische Klasse. 1918:235
Kosmann-Schwarzbach Y (2010) The Noether theorems: invariance and conservation laws in the twentieth century. Sources and Studies in the History of Mathematics and Physical Sciences. Springer, Berlin
Kara AH, Vawda FE, Mahomed FM (1994) Symmetries of first integrals and solutions of differential equations. Lie Groups Appl 1:27
Bokhari AH, Al-Dweik AY, Zaman FD, Kara AH, Mahomed FM (2010) Generalization of the double reduction theory. Nonlinear Analysis B 11:3763
Ali S, Mahomed FM, Qadir A (2008) Complex Lie symmetries for variational problems. J Nonlin Math Phys 25:25
Zimmerman AH (1987) Generalized integral transformations. Dover Publications, Mineola
Tassaddiq A (2012) Some representations of the extended Fermi-Dirac and Bose-Einstein functions with application. NUST CAMP
Tassaddiq A, Qadir A (2011) Fourier transform and distributional representation of the generalized gamma function with some applications. Appl Math Comp 218:1084
Bender CM, Boetcher S (1998) Real spectra in non-Hermitian Hamiltonians having PT symmetry. Phys Rev Lett 80:5243
Safdar M, Qadir A, Farooq MU (2019) Comparison of Noether symmetries and first integrals of two-dimensional systems of second order ordinary differential equations by real and complex methods. Symmetry 11:1180
Farooq MU, Ali S, Qadir A (2010) Invariants of two-dimensional systems via complex Lagrangians with applications. Commun Nonlin Sci Num Sim 16:1804
Kara AH, Mahomed FM (2006) Noether-type symmetries and conservation laws via partial Lagrangians. Nonlinear Dyn 45:367
Qadir A, Mahomed FM (2015) Higher dimensional systems of differential equations obtainable by iterative use of complex methods. Int J Mod Phys (Conf Ser) 38:1560077. In: Ali S, Mahomed FM, Qadir A (eds)
Leach PGL, Maartens R, Maharaj SD (1992) Self-similar solutions of the generalized Emden-Fowler equation. Int J Non-Linear Mech 27:583
Gonzalez-Gascon F, Gonzalez-Lopez A (1988) Newtonian systems of differential equations, integrable via quadratures, with trivial group of point symmetry. Phys Lett A 129:153
Mahomed KS, Momoniat E (2014) Symmetry classification of first integrals for scalar dynamical equations. Int J Non-Linear Mech 59:52
Safdar M, Ali S, Mahomed FM (2011) Linearization of systems of four second order ordinary differential equations. Pramana - J Phys 77:171834
Dutt HM, Safdar M, Qadir A (2019) Linearization criteria for two dimensional systems of third order ordinary differential equations by complex approach. Arabian J Math 8:163
Dutt HM, Safdar M, Qadir A (2018) Classification of two-dimensional linearizable systems of third order ordinary differential equations by complex methods. In: Aslam MJ, Saifullah K (eds) Proceedings of the \(14^{th}\) regional conference in mathematical physics, pp 278–283, 2015. World Scientific
Dutt HM, Qadir A (2014) Reduction of fourth order ordinary differential equations to second and third Lie linearizable forms. Comm Nonlin Sci Numerical Sim 19:2653
Dutt HM, Qadir A (2017) Classification of scalar third order ordinary differential equations linearizable via generalized contact transformations. Quaestiones Mathematicae 2017:1
Dutt HM, Qadir A (2018) Classification of scalar fourth order ordinary differential equations linearizable via generalized Lie-Bäcklund transformations. In: Kac VG, Olver PJ, Winternitz P, Özer T (eds)Proceedings of the symmetries, differential equations and applications III, pp 67–74. Springer Proceedings in Mathematics & Statistics
Acknowledgements
We are grateful to Rimsha Khalil for pointing out some typographical errors in the chapter. FMM is grateful to the NRF of South Africa for support.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2021 Higher Education Press
About this chapter
Cite this chapter
Qadir, A., Mahomed, F.M. (2021). Complex Methods for Lie Symmetry Analysis. In: Luo, A.C.J., Gazizov, R.K. (eds) Symmetries and Applications of Differential Equations. Nonlinear Physical Science. Springer, Singapore. https://doi.org/10.1007/978-981-16-4683-6_4
Download citation
DOI: https://doi.org/10.1007/978-981-16-4683-6_4
Published:
Publisher Name: Springer, Singapore
Print ISBN: 978-981-16-4682-9
Online ISBN: 978-981-16-4683-6
eBook Packages: Mathematics and StatisticsMathematics and Statistics (R0)