We consider the partial difference equations of the Adler-Bobenko-Suris classification, which are characterized as multidimensionally consistent. The latter property leads naturally to the construction of auto-Bäcklund transformations and Lax pairs for all the equations in this class. Their symmetry analysis is presented and infinite hierarchies of generalized symmetries are explicitly construc...

Isospectral theory of the Lax pairs of both 3D and 2D Euler equations of inviscid fluids is developed. Eigenfunctions are represented through an ergodic integral. The Koopman group and mean ergodic theorem are utilized. Further harmonic analysis results on the ergodic integral are introduced. The ergodic integral is a limit of the oscillatory integral of the first kind.

The correspondance is established between the sigma models , the minimal surfaces and the Monge-Ampére equation. The Lax-Pairs of the minimality condition of the minimal surfaces and the MongeAmpére equations are given. Existance of infinitely many nonlocal conservation laws is shown and some Backlund transformations are also given.

We recently introduced a class of ZN graded discrete Lax pairs and studied the associated discrete integrable systems (lattice equations). In particular, we introduced a subclass, which we called “self-dual”. In this paper we discuss the continuous symmetries of these systems, their reductions and the relation of the latter to the Bogoyavlensky equation.

Based on the Bell polynomials scheme, this paper presents a Maple computer algebra program PDEBellII which can automatically construct the bilinear forms, bilinear Bäcklund transformations, Lax pairs and conservation laws of the KdV-type soliton equations. Some examples are given to verify the validity of our program.

A relationship between Painlevé systems and infinite-dimensional integrable hierarchies is studied. We derive a class of higher order Painlevé systems from Drinfeld-Sokolov (DS) hierarchies of type A by similarity reductions. This result allows us to understand some properties of Painlevé systems, Hamiltonian structures, Lax pairs and affine Weyl group symmetries. 2000 Mathematics Subject Class...

In this paper, semi-discretizations and full-discretization of the Leznov lattice are investigated via Hirota’s bilinear formalism. As a result, two integrable semi-discrete versions and one fully discrete version for the Leznov lattice are found. Bäcklund transformations, nonlinear superposition formulae and Lax pairs for these discrete versions are presented. Mathematics Subject Classificatio...