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Polygonal side-strip data

Definition
PolygonalSideStrips

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

crossing-consequencespolygonal-geometry

A collar together with left and right open connected side strips around a polygonal arc. The strips are disjoint from the arc and from each other, cover the collar away from the relative interior, and have the relative interior in each strip closure.

Definition code
import Definitions.Def_PolygonalArc

-- [TABLET NODE: PolygonalSideStrips]
-- Source: https://github.com/wpegden/crossing-consequences/blob/8769d142033fce042f502bf2857afb6b1375b5c3/Tablet/PolygonalSideStrips.lean#L1-L25
structure PolygonalSideStrips (γ : PolygonalArc) where
  collar : Set (EuclideanSpace ℝ (Fin 2))
  leftStrip : Set (EuclideanSpace ℝ (Fin 2))
  rightStrip : Set (EuclideanSpace ℝ (Fin 2))
  collar_open : IsOpen collar
  left_open : IsOpen leftStrip
  right_open : IsOpen rightStrip
  relativeInterior_subset_collar : γ.relativeInterior ⊆ collar
  left_subset_collar : leftStrip ⊆ collar
  right_subset_collar : rightStrip ⊆ collar
  left_connected : IsConnected leftStrip
  right_connected : IsConnected rightStrip
  left_disjoint_arc : Disjoint leftStrip γ.carrier
  right_disjoint_arc : Disjoint rightStrip γ.carrier
  side_strips_disjoint : Disjoint leftStrip rightStrip
  relativeInterior_subset_closure_left :
    γ.relativeInterior ⊆ closure leftStrip
  relativeInterior_subset_closure_right :
    γ.relativeInterior ⊆ closure rightStrip
  collar_without_arc :
    collar \ γ.relativeInterior = leftStrip ∪ rightStrip
Source
https://github.com/wpegden/crossing-consequences/blob/8769d142033fce042f502bf2857afb6b1375b5c3/Tablet/PolygonalSideStrips.lean

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