The Inverse Problem for a Discrete Periodic Schrodinger Operator

We study isospectral sets for a discrete 1D Schrodinger operator on ℤ with an (N + 1)-periodic potential. We show that for small odd potentials, the isospectral set consists of 2^{(N + 1)/2} elements, while for large potentials, the isospectral set consists of (N +1)! elements. Moreover, asymptotics for endpoints of the spectrum of the Schrodinger operator for small (and large) potentials are determined. Bibliography: 5 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 315, 2004, pp. 96–101.