A new method for solving completely integrable PDEs

TL;DR

This paper introduces a universal method for solving completely integrable PDEs by encoding scattering data into a special matrix function, simplifying the inverse scattering process and unifying the treatment of various equations.

Contribution

The work presents a novel approach that encodes scattering data into a special matrix function, enabling a unified and simplified solution process for a wide class of integrable PDEs.

Findings

The method applies to equations like KdV and NLS.

It simplifies the inverse scattering process.

It generalizes to PDEs with multiple variables.

Abstract

The inverse scattering theory is a basic tool to solve linear differential equations and some Partial Differential Equations (PDEs). Using this theory the Korteweg-de Vries (KdV), the family of evolutionary Non Linear Schrodinger (NLS) equations, Kadomtzev-Petviashvili and many more completely integrable PDEs of mathematical physics are solved, using Zacharv-Shabath scheme. This last approach includes the use of a Lax pair, and has an advantage to be applied to wider class of equations, like difference equations, but has a disadvantage to be used only for "rapidly decreasing solutions". This technique is also intimately related to completely integrable systems. The identifying process of a Lax pair, a system and finally the "scattering data" is usually a difficult process, simplified in many cases by physicals models providing clues of how the scattering data should be chosen. In this work we show that the scattering data can be encoded into singularities of a very special mathematical object: J-unitary, identity at infinity matrix-valued function, which, if evolved once, solves the inverse scattering theory, if evolved twice solves evolutionary PDEs. The provided scheme seems to be universal in the sense that many (if not all) completely integrable PDEs arise (or should arise) in this manner by changing the so called "vessel parameters" (for examples, solutions of KdV and evolutionary NLS equations are presented). The results presented here allow to study different flows (commuting and non-commuting) in a unified approach and provide a rich mathematical arsenal to study these equations. The results are easily generalized to completely integrable PDEs of n (may be infinity) variables.