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All available vertices give a joint budget along a graph geodesic

Proved
Hirsch.geodesic_joint_budget_of_all_available_contacts

by jjosh · Sep 12, 2026 · Mathlib c5ea003 (Lean v4.30.0)

formalizationgraph-theorypolyhedra

Let p be a metric-shortest path in an undirected simple graph. Let A be any finite set of available vertices, including vertices off the path, and let L be a duplicate-free list of vertices on p. Suppose each selected vertex i has a nonnegative integer budget delta_i satisfying delta_i + |A| <= e + #{j in A : j=i or j is adjacent to i}. Then sum_i delta_i + |L|*|A| <= |L|*e + 3|A|. In particular when |A|=e the total budget is at most 3e.

Each available vertex contacts a window of at most three path positions: otherwise it supplies a two-edge shortcut. Double-count those contacts and sum the pointwise inequalities. True metric shortestness is essential. This theorem is a graph and integer-budget statement. The separate repository adapter proves its applicability to actual clipping carrier excesses; the statement itself neither identifies delta with edge distance nor resolves the Polynomial Hirsch conjecture.

Preamble
import Mathlib
open scoped BigOperators
open Set
Formal statement
theorem Hirsch.geodesic_joint_budget_of_all_available_contacts {V : Type*} [DecidableEq V] {G : SimpleGraph V} [DecidableRel G.Adj]
    {u v : V} (p : G.Walk u v) (hp : p.length = G.dist u v)
    (available : Finset V) (labels : List V) (hnd : labels.Nodup)
    (hsub : ∀ i ∈ labels, i ∈ p.support) (delta : V → ℕ) (e : ℕ)
    (hbudget : ∀ i ∈ labels, delta i + available.card ≤ e +
      (available.filter (fun j => j = i ∨ G.Adj j i)).card) :
    (labels.map delta).sum + labels.length * available.card ≤
      labels.length * e + 3 * available.card := by sorry
Source
Geodesic shortcut and double-counting formalization, https://github.com/jjoshua2/prove2me-work/tree/21b4413f294d4503aa98b2c0ded939595724108e

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