Inverse problem for the L-operator in the Lax Pair of the Boussinesq equation on the circle

Abstract

We consider a third-order non-self-adjoint operator, which is an $L$-operator in the Lax pair for the Boussinesq equation on the circle. We construct a mapping from the set of operator coefficients to the set of spectral data, similar to the corresponding mapping for the Hill operator constructed by E. Korotyaev. We prove that in a neighborhood of zero our mapping is analytic and one-to-one.