Periodic perturbations of unbounded Jacobi matrices I: Asymptotics of   generalized eigenvectors
  We study asymptotics of generalized eigenvectors associated with Jacobi matrices. Under weak conditions on the coefficients we identify when the matrices are self-adjoint and show that they satisfy strong non-subordinacy condition. 
Grzegorz \'Swiderski and Bartosz Trojan
math.SP math.CA