This paper continues the analysis of the scattering problem for a network of open
wave-guides started in Parts I and II. In this part we present explicit, physically
motivated radiation conditions that ensure uniqueness of the solution to the
scattering problem. These conditions stem from a paper of Vasy (2000) on 3-body
Schrödinger operators; we also discuss closely related conditions from a paper of
Isozaki (1994). Vasy’s paper also proves the existence of the limiting absorption
resolvents, and that the limiting solutions satisfy the radiation conditions. The
statements of these results require a calculus of pseudodifferential operators, called
the 3-body scattering calculus, which is briefly introduced here. We show
that the solutions to the model problems obtained in Part I satisfy these
radiation conditions, which makes it possible to prove uniqueness, and therefore
existence, for the system of Fredholm integral equations introduced in that
paper.
Keywords
open wave-guide network, scattering, Isozaki/Melrose/Vasy
radiation conditions, uniqueness, outgoing solution,
scattering wave-front set, Fredholm integral equation
uniqueness