N-fold Bäcklund transformation for the Davey-Stewartson equation is constructed by
using the analytic structure of the Lax eigenfunction in the complex eigenvalue plane.
Explicit formulae can be obtained for a specified value of N. Lastly it is shown how
generalized soliton solutions are generated...
The characteristic representation, or Goursat problem, for the Klein-Fock-Gordon
equation with Volkov interaction  is regarded. It is shown that in this representation
the explicit form of the Volkov propagator can be obtained. Using the characteristic
representation technique, the Schwinger integral...
We analyse the behaviour of the Dirac equation in d = 1 + 1 with Lorentz scalar
potential. As the system is known to provide a physical realization of supersymmetric
quantum mechanics, we take advantage of the factorization method in order to enlarge
the restricted class of solvable problems. To be...
Infinite-dimensional algebra of all infinitesimal transformations of solutions of the
self-dual Yang-Mills equations is described. It contains as subalgebras the infinitedimensional algebras of hidden symmetries related to gauge and conformal transformations.
This paper describes a new algorithm for determining all discrete contact symmetries
of any differential equation whose Lie contact symmetries are known. The method
is constructive and is easy to use. It is based upon the observation that the adjoint
action of any contact symmetry is an automorphism...
A concept of asymptotic symmetry is introduced which is based on a definition of
symmetry as a reducibility property relative to a corresponding invariant ansatz. It is
shown that the nonlocal Lorentz invariance of the free-particle Schrödinger equation,
discovered by Fushchych and Segeda in 1977,...
The conventional theory of resonance broadening for a two-species plasma in a magnetic field is revised, and applied to an ionospheric turbulence case. The assumptions
made in the conventional theory of resonance broadening have, in the past, led to
replacing the frequency by + ik2
in the resonant...
The fundamental problem of Farley-Buneman turbulence in the auroral E-region has
been discussed and debated extensively in the past two decades. In the present paper
we intend to clarify the different steps that the auroral E-region plasma has to undergo
before reaching a steady state. The mode-coupling...
Abstract telegrapher's equations and some random walks of Poisson type are shown
to fit into the framework of the Hamiltonian formalism after an appropriate timedependent rescaling of the basic variables has been made.