Abstract

Riemann’s method is one of the definitive ways of solving Cauchy’s problem for a second order linear hyperbolic partial differential equation in two variables. The first review of Riemann’s method was published by E.T. Copson in 1958. This study extends that work. Firstly, three solution methods were overlooked in Copson’s original paper. Secondly, several new approaches for finding Riemann functions have been developed since 1958. Those techniques are included here and placed in the context of Copson’s original study. There are also numerous equivalences between Riemann functions that have not previously been identified in the literature. Those links are clarified here by showing that many known Riemann functions are often equivalent due to the governing equation admitting a symmetry algebra isomorphic to S L ( 2 , R ) . Alternatively, the equation admits a Lie-Bäcklund symmetry algebra. Combining the results from several methods, a new class of Riemann functions is then derived which admits no symmetries whatsoever.

Highlights

  • The interest in Riemann’s method is long-standing

  • The reason is that once the Riemann function is determined, the governing equation can be solved for Cauchy data on any other non-characteristic curve

  • Copson [24] wrote the first review of Riemann’s method in 1958. He listed six different techniques to solve for the Riemann function

Read more

Summary

Introduction

The reason is that once the Riemann function is determined, the governing equation can be solved for Cauchy data on any other non-characteristic curve. The value of such a property means that Riemann’s method continues to draw the attention of investigators today. Copson [24] wrote the first review of Riemann’s method in 1958 He listed six different techniques to solve for the Riemann function. R(r, s, r0 , s0 ) is called the Riemann function It is the solution of the characteristic boundary value problem for the adjoint equation denoted by (3)–(6).

Copson’s Review
Self Adjoint Riemann Functions
Methods not Included by Copson
The Telegrapher’s Equation
Successive Iterations and the Banach Fixed Point Principle
Olevskiı’s Addition Formula
Developments Since 1958
Lie Point Symmetries
Laplace Transform for a Klein-Gordon Equation with a Non-Constant Coefficient
The Multiplication Formula
Finite Groups and a Link to Appell’s F4
Lie-Bäcklund Symmetries
New Riemann Functions
Conclusions

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.