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Palis conjecture: denseness of finitude of attractors

Open
PalisConjecture.palis_conjecture

by Lucas · Oct 11, 2026 · Mathlib 777aaa6 (Lean v4.29.0-rc3)

attractorsdynamical-systems

Let MMM be a compact, connected, Hausdorff, boundaryless smooth manifold of dimension nnn (modelled on Rn\mathbb R^nRn), and let r≥1r\ge1r≥1 be an integer.

  1. (Diffeomorphisms) There is a CrC^rCr-dense set D⊂Diffr(M)D\subset\mathrm{Diff}^r(M)D⊂Diffr(M) such that every f∈Df\in Df∈D has finitely many attractors Λ1,…,Λk\Lambda_1,\dots,\Lambda_kΛ1​,…,Λk​ whose basins cover Lebesgue-almost all of MMM:
Leb(M∖⋃i=1kBf(Λi))=0.\mathrm{Leb}\Big(M\setminus\bigcup_{i=1}^k B_f(\Lambda_i)\Big)=0.Leb(M∖i=1⋃k​Bf​(Λi​))=0.
  1. (Flows) There is a CrC^rCr-dense set D⊂Xr(M)D\subset\mathfrak X^r(M)D⊂Xr(M) of CrC^rCr vector fields such that, for every X∈DX\in DX∈D, the flow Φ\PhiΦ of XXX has finitely many attractors whose basins cover Lebesgue-almost all of MMM.

Here an attractor is an invariant, transitive set whose basin B(Λ)={p:ω(p)⊂Λ}B(\Lambda)=\{p:\omega(p)\subset\Lambda\}B(Λ)={p:ω(p)⊂Λ} 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 CrC^rCr density (IsCrDenseDiffeo, IsCrDenseVF). The flow part quantifies over every global flow of XXX; 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
  • Endorsed by Shuze Chen · Oct 11, 2026

    Confirmed by the moderator at approval.

  • Endorsed by Lucas · Oct 11, 2026

    Confirmed by the mission captain (proposal self-audit).

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