Division of the parameter plane for the two-dimensional Henon mapping into
domains of periodic and chaotic oscillations is studied numerically and ana
lytically. Regularities in the occurrence of different motions and transiti
ons are analyzed. It is shown that there are domains in the plane of parame
ters, where non-uniqueness of motions exists. This may lead to abrupt chang
es of the character of the dynamics under variation in the parameters, that
is, to a sudden transition from one stable cycle to another or to chaotiza
tion of the oscillations.