Decays of degeneracies in PT-symmetric ring-shaped lattices

Many apparently non-Hermitian ring-shaped discrete lattices share the appeal with their more popular linear predecessors. Irrespectively of the change of the topology, their dynamics controlled by the nearest-neighbor interaction is shown to remain phenomenologically interesting. For the perturbation-caused removals of spectral degeneracy at exceptional points, in particular, alternative scenarios are illustrated via solvable examples. (C) 2011 Elsevier B.V. All rights reserved.