David Damanik, Rowan Killip, Barry Simon
Perturbations of Orthogonal Polynomials With Periodic Recursion Coefficients
(193K, LaTeX)

ABSTRACT.  We extend the results of Denisov-Rakhmanov, Szego-Shohat-Nevai, 
and Killip-Simon from asymptotically constant orthogonal polynomials on the real line (OPRL) and unit circle (OPUC) to asymptotically periodic OPRL and OPUC. The key tool is a characterization of the isospectral torus that is well adapted to the study of perturbations.