Skip to content
Open
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
38 changes: 38 additions & 0 deletions LeanEval/Topology/Poincare3DTopological.lean
Original file line number Diff line number Diff line change
@@ -0,0 +1,38 @@
import Mathlib
import EvalTools.Markers

namespace LeanEval
namespace Topology

/-!
# 3D topological Poincaré conjecture (Perelman)

A `proof_wanted` in `Mathlib/Geometry/Manifold/PoincareConjecture.lean`. Every
simply connected compact Hausdorff 3-manifold is homeomorphic to the standard
3-sphere `𝕊³`.

Proved by Grigori Perelman in 2002–2003 via Hamilton's Ricci flow with surgery
(Perelman's three preprints on the arXiv; Fields Medal awarded but declined,
2006; Clay Millennium Prize awarded 2010, also declined). One of the seven
original Millennium Problems.

mathlib has `ChartedSpace`, `SimplyConnectedSpace`, `CompactSpace`, `T2Space`,
`Homeomorph` (`≃ₜ`), and the unit sphere as a smooth manifold but no
Ricci flow, no Hamilton–Perelman surgery, and no Poincaré conjecture itself.
-/

open Metric (sphere)

/-- **3D topological Poincaré conjecture** (Perelman, 2002–2003). Every
simply connected compact Hausdorff 3-manifold is homeomorphic to the
standard 3-sphere `𝕊³`. -/
@[eval_problem]
theorem poincare_3d_topological
{M : Type*} [TopologicalSpace M] [T2Space M]
[ChartedSpace (EuclideanSpace ℝ (Fin 3)) M]
[SimplyConnectedSpace M] [CompactSpace M] :
Nonempty (M ≃ₜ sphere (0 : EuclideanSpace ℝ (Fin 4)) 1) := by
sorry

end Topology
end LeanEval
11 changes: 11 additions & 0 deletions manifests/problems.toml
Original file line number Diff line number Diff line change
Expand Up @@ -682,3 +682,14 @@ module = "LeanEval.Geometry.Uniformization"
holes = ["uniformization"]
submitter = "Junyan Xu"
source = "John Hamal Hubbard, *Teichmüller theory and applications to geometry, topology, and dynamics. Vol. 1*, Chapter 1."

[[problem]]
id = "poincare_3d_topological"
title = "3D topological Poincaré conjecture (Perelman)"
test = false
module = "LeanEval.Topology.Poincare3DTopological"
holes = ["poincare_3d_topological"]
submitter = "Kim Morrison"
notes = "Every simply connected compact Hausdorff 3-manifold is homeomorphic to 𝕊³. Recorded as `proof_wanted SimplyConnectedSpace.nonempty_homeomorph_sphere_three` in `Mathlib/Geometry/Manifold/PoincareConjecture.lean`. Proved by Perelman in 2002-2003 via Hamilton's Ricci flow with surgery; one of the seven Millennium Problems. Mathlib has ChartedSpace, SimplyConnectedSpace, CompactSpace, T2Space, Homeomorph and the unit sphere as a smooth manifold but no Ricci flow, no Hamilton-Perelman surgery, and no Poincaré conjecture itself."
source = "G. Perelman, The entropy formula for the Ricci flow and its geometric applications (arXiv:math/0211159, 2002); Ricci flow with surgery on three-manifolds (arXiv:math/0303109, 2003); Finite extinction time for the solutions to the Ricci flow on certain three-manifolds (arXiv:math/0307245, 2003). Recorded as a `proof_wanted` in Mathlib/Geometry/Manifold/PoincareConjecture.lean. Originally conjectured by Henri Poincaré in 1904."
informal_solution = "Run Ricci flow ∂g/∂t = -2 Ric(g) on M with surgery to remove finite-time singularities (Hamilton's program, completed by Perelman). The flow simplifies the metric, and Perelman's monotonicity formulas (reduced volume, ℒ-functional, no local collapsing) together with the canonical-neighbourhood theorem control the geometry. In finite time the flow either becomes extinct (M is a connected sum of spherical space forms and S²×S¹s, in particular when π_1(M) = 1, M = S³) or decomposes M along incompressible 2-tori into pieces of one of Thurston's eight geometric types; the simply-connected hypothesis rules out the toroidal decomposition and the spherical-space-form ambiguity, leaving M ≃ S³."
Loading