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OpenConnectedComponentPolygonallyConnected

Proved
OpenConnectedComponentPolygonallyConnected

by xuanji · Sep 27, 2026 · Mathlib 0df444a (Lean v4.33.1)

crossing-consequencesgeometrypolygonal

Every connected component of the complement of an open set in the Euclidean plane is polygonally path connected: any two points in the component can be joined by a polygonal path contained in that component.

Preamble
import Definitions.Def_ComplementComponent
import Definitions.Def_PolygonallyPathConnected
Formal statement
lemma OpenConnectedComponentPolygonallyConnected
    (U C : Set (EuclideanSpace ℝ (Fin 2))) :
    IsOpen U → ComplementComponent Uᶜ C → PolygonallyPathConnected C := by sorry
Source
https://github.com/wpegden/crossing-consequences/blob/8769d142033fce042f502bf2857afb6b1375b5c3/Tablet/OpenConnectedComponentPolygonallyConnected.lean#L1-102

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