Palis conjecture: denseness of finitude of attractors
OpenPalisConjecture.palis_conjectureattractorsdynamical-systems
Let be a compact, connected, Hausdorff, boundaryless smooth manifold of dimension (modelled on ), and let be an integer.
- (Diffeomorphisms) There is a -dense set such that every has finitely many attractors whose basins cover Lebesgue-almost all of :
- (Flows) There is a -dense set of vector fields such that, for every , the flow of has finitely many attractors whose basins cover Lebesgue-almost all of .
Here an attractor is an invariant, transitive set whose basin has positive Lebesgue measure.
This is the conjecture of J. Palis as stated on the Open Problem Garden. It replaces the false hope that hyperbolic systems are dense by a statistical description of a dense set of systems.
Formalization Note Density is sequential density (IsCrDenseDiffeo, IsCrDenseVF). The flow part quantifies over every global flow of ; such a flow exists and is unique (see the flow-existence milestone).
Preamble
import Mathlib import Definitions.Def_palis_lebesgue_null import Definitions.Def_palis_attractor import Definitions.Def_palis_vector_field import Definitions.Def_palis_cr_topology open scoped Manifold ContDiff
Formal statement
namespace PalisConjecture
theorem palis_conjecture (n : ℕ) {M : Type*} [TopologicalSpace M] [T2Space M]
[CompactSpace M] [ConnectedSpace M] [ChartedSpace (EuclideanSpace ℝ (Fin n)) M]
[IsManifold (𝓡 n) ∞ M] (r : ℕ) (hr : 1 ≤ r) :
(∃ D : Set (M ≃ₘ^(r : WithTop ℕ∞)⟮𝓡 n, 𝓡 n⟯ M), IsCrDenseDiffeo r D ∧
∀ f ∈ D, HasFiniteAttractorsCoveringAE n (f : M → M)) ∧
(∃ D : Set ((x : M) → TangentSpace (𝓡 n) x), (∀ X ∈ D, IsCrVectorField r X) ∧
IsCrDenseVF r D ∧
∀ X ∈ D, ∀ Φ : ℝ → M → M, IsFlowOf X Φ → FlowHasFiniteAttractorsCoveringAE n Φ) := by
sorry
end PalisConjecture
Source
Open Problem Garden, "Jacob Palis Conjecture (Finitude of Attractors) (Dynamical Systems)", posted by Jailton Viana, April 24, 2013, https://www.openproblemgarden.org/op/jacob_palis_conjecture_finitude_of_attractors_dynamical_systems (Conjecture box and the Definition of attractor below it); bibliography: C. Bonatti, L. J. Diaz, M. Viana, Dynamics Beyond Uniform Hyperbolicity, Encyclopaedia of Mathematical Sciences 102, Springer, 2005.
Human review
Confirmed by the mission captain (proposal self-audit).
Confirmed by the moderator at approval.