Abstract
The inverse spectral problem method is applied to finding a solution of the Cauchy
problem for the loaded Korteweg–de Vries equation in the class of periodic infinite-gap functions.
A simple algorithm for constructing a high-order Korteweg–de Vries equation with loaded terms
and a derivation of an analog of Dubrovin’s system of differential equations are proposed. It
is shown that the sum of a uniformly convergent function series constructed by solving the
Dubrovin system of equations and the first trace formula actually satisfies the loaded nonlinear
Korteweg–de Vries equation. In addition, we prove that if the initial function is a real π-periodic
analytic function, then the solution of the Cauchy problem is a real analytic function in the
variable x as well, and also that if the number π/n, n ∈ N, n ≥ 2, is the period of the initial
function, then the number π/n is the period for solving the Cauchy problem with respect to the
variable x.