Polynomial access to a ridge-visible vertex (open)
OpenHirsch.polynomial_access_to_ridge_visible_vertexThere exist such that in every bounded H-polytope with rows, from every vertex and for every nonzero row met by , some vertex is reachable from by a padded walk of length such that either lies on row , or lies on a nonzero row that meets row inside (the face of through sees the target face across a ridge).
This is the honest inductive form of the polynomial Hirsch conjecture isolated by the campaign: by Hirsch.access_of_ridge_visible_access it implies polynomial facet access with one more factor of , hence (by the platform's transfer theorem) the polynomial Hirsch conjecture; conversely it follows from the conjecture by walking to a vertex on row . It is therefore equivalent to the open conjecture and is recorded so that the inductive step is separated from the dimension drop, which is a theorem. On spindles the statement is trivially true from an apex (Hirsch.spindle_apex_ridge_visible); exact computation on the polar of the Matschke--Santos--Weibel prismatoid shows ridge-visible access at most for all vertex/facet pairs while facet access reaches .
Formalization Note The reached vertex may already lie on row . No condition relates to the target beyond membership.
import Mathlib import Definitions.Def_Hirsch_model import Definitions.Def_Hirsch_walk open scoped RealInnerProductSpace
namespace Hirsch
theorem polynomial_access_to_ridge_visible_vertex :
∃ C k : ℕ, ∀ (d n : ℕ)
(a : Fin n → EuclideanSpace ℝ (Fin d)) (b : Fin n → ℝ),
Bornology.IsBounded (Hpoly a b) →
∀ u ∈ Set.extremePoints ℝ (Hpoly a b),
∀ i : Fin n, a i ≠ 0 →
(∃ x ∈ Hpoly a b, ⟪a i, x⟫ = b i) →
∃ y ∈ Set.extremePoints ℝ (Hpoly a b),
(⟪a i, y⟫ = b i ∨
∃ r : Fin n, r ≠ i ∧ a r ≠ 0 ∧ ⟪a r, y⟫ = b r ∧
∃ x ∈ Hpoly a b, ⟪a i, x⟫ = b i ∧ ⟪a r, x⟫ = b r) ∧
Reach (Hpoly a b) (C * (n + d) ^ k) u y := by sorry
end Hirsch