Copyright © 2009 G. Bastien and M. Rogalski. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We study order Lyness' difference equation in , with and the associated dynamical system in . We study its solutions (divergence, permanency, local stability of the equilibrium). We prove some results, about the first three invariant functions and the topological nature of the
corresponding invariant sets, about the differential at the equilibrium, about the role of 2-periodic points when is odd, about the nonexistence of some minimal periods, and so forth and discuss some problems, related to the search of common period to all solutions, or to the second and third invariants. We
look at the case with new methods using new invariants for the map and state some conjectures on the associated dynamical system in in more general cases.