3 research outputs found
Classification of polynomial integrable systems of mixed scalar and vector evolution equations. I
We perform a classification of integrable systems of mixed scalar and vector
evolution equations with respect to higher symmetries. We consider polynomial
systems that are homogeneous under a suitable weighting of variables. This
paper deals with the KdV weighting, the Burgers (or potential KdV or modified
KdV) weighting, the Ibragimov-Shabat weighting and two unfamiliar weightings.
The case of other weightings will be studied in a subsequent paper. Making an
ansatz for undetermined coefficients and using a computer package for solving
bilinear algebraic systems, we give the complete lists of 2nd order systems
with a 3rd order or a 4th order symmetry and 3rd order systems with a 5th order
symmetry. For all but a few systems in the lists, we show that the system (or,
at least a subsystem of it) admits either a Lax representation or a linearizing
transformation. A thorough comparison with recent work of Foursov and Olver is
made.Comment: 60 pages, 6 tables; added one remark in section 4.2.17 (p.33) plus
several minor changes, to appear in J.Phys.
Classical R-matrix theory for bi-Hamiltonian field systems
The R-matrix formalism for the construction of integrable systems with
infinitely many degrees of freedom is reviewed. Its application to Poisson,
noncommutative and loop algebras as well as central extension procedure are
presented. The theory is developed for (1+1)-dimensional case where the space
variable belongs either to R or to various discrete sets. Then, the extension
onto (2+1)-dimensional case is made, when the second space variable belongs to
R. The formalism presented contains many proofs and important details to make
it self-contained and complete. The general theory is applied to several
infinite dimensional Lie algebras in order to construct both dispersionless and
dispersive (soliton) integrable field systems.Comment: review article, 39 page