1,081 research outputs found
Stabilization of heterodimensional cycles
We consider diffeomorphisms with heteroclinic cycles associated to
saddles and of different indices. We say that a cycle of this type can
be stabilized if there are diffeomorphisms close to with a robust cycle
associated to hyperbolic sets containing the continuations of and . We
focus on the case where the indices of these two saddles differ by one. We
prove that, excluding one particular case (so-called twisted cycles that
additionally satisfy some geometrical restrictions), all such cycles can be
stabilized.Comment: 31 pages, 9 figure
On maximal transitive sets of generic diffeomorphisms
We construct locally generic C1-diffeomorphisms of 3-manifolds with maximal transitive Cantor sets without periodic points. The locally generic diffeomorphisms constructed also exhibit strongly pathological features general-izing the Newhouse phenomenon (coexistence of infinitely many sinks or sources). Two of these features are: coex-istence of infinitely many nontrivial (hyperbolic and nonhyperbolic) attractors and repellors, and coexistence of in-finitely many nontrivial (nonhyperbolic) homoclinic classes. We prove that these phenomena are associated to the existence of a homoclinic class H(P, f) with two spe-cific properties: – in a C1-robust way, the homoclinic class H(P, f) does not admit any dominated splitting, – there is a periodic point P ′ homoclinically related to P such that the Jacobians of P ′ and P are greater than and less than one, respectively. 1
Cantor Spectrum for Schr\"odinger Operators with Potentials arising from Generalized Skew-shifts
We consider continuous -cocycles over a strictly ergodic
homeomorphism which fibers over an almost periodic dynamical system
(generalized skew-shifts). We prove that any cocycle which is not uniformly
hyperbolic can be approximated by one which is conjugate to an
-cocycle. Using this, we show that if a cocycle's homotopy
class does not display a certain obstruction to uniform hyperbolicity, then it
can be -perturbed to become uniformly hyperbolic. For cocycles arising
from Schr\"odinger operators, the obstruction vanishes and we conclude that
uniform hyperbolicity is dense, which implies that for a generic continuous
potential, the spectrum of the corresponding Schr\"odinger operator is a Cantor
set.Comment: Final version. To appear in Duke Mathematical Journa
Infinitely Many Stochastically Stable Attractors
Let f be a diffeomorphism of a compact finite dimensional boundaryless
manifold M exhibiting infinitely many coexisting attractors. Assume that each
attractor supports a stochastically stable probability measure and that the
union of the basins of attraction of each attractor covers Lebesgue almost all
points of M. We prove that the time averages of almost all orbits under random
perturbations are given by a finite number of probability measures. Moreover
these probability measures are close to the probability measures supported by
the attractors when the perturbations are close to the original map f.Comment: 14 pages, 2 figure
Aperiodic invariant continua for surface homeomorphisms
We prove that if a homeomorphism of a closed orientable surface S has no
wandering points and leaves invariant a compact, connected set K which contains
no periodic points, then either K=S and S is a torus, or is the
intersection of a decreasing sequence of annuli. A version for non-orientable
surfaces is given.Comment: 8 pages, to appear in Mathematische Zeitschrif
Non-hyperbolic ergodic measures with large support
We prove that there is a residual subset in
such that, for every , any homoclinic class of with
invariant one dimensional central bundle containing saddles of different
indices (i.e. with different dimensions of the stable invariant manifold)
coincides with the support of some invariant ergodic non-hyperbolic (one of the
Lyapunov exponents is equal to zero) measure of
- …