Theorem 7, p. 1434 — the VRHS production cut (32) along a chain c₁ ≺ ⋯ ≺ c_n is valid for PCPSP-F, and for PCPSP-P under (33)
ProvedOpenPitMIP.Vrhs.theorem_7Consider an instance of the PCPSP-C satisfying the standing assumptions. Fix a destination , a period and clusters () such that
- ,
- ,
- .
Let and for , and , . Let for , and consider, with , the inequality
Then (32) holds at every feasible for the PCPSP-F that satisfies the destination capacity rows (9). If moreover
then (32) holds at every feasible for the PCPSP-P that satisfies (9).
The VRHS cuts couple the precedence structure along a chain with the capacity of one destination: they tighten the linear relaxation of the PCPSP-C at points that send heavy successors of a partially extracted cluster to a capacitated destination.
Formalization Note "Valid for PCPSP-F (PCPSP-P)" is read as: valid at every point feasible for (1)–(7) with integrality (10) (resp. (11)) whose side constraints include the destination capacity rows (9) (p. 1427: "constraints (5) typically include conditions of the form (8), (9)"); (9) is an explicit hypothesis. Condition 1 is stated for consecutive pairs; the chain is c : ℕ → C read at . Periods are Fin T (index is period ); is taken at the single period and is cumulative.
import Mathlib import Definitions.Def_OpenPitMIP_Vrhs_Setting
namespace OpenPitMIP.Vrhs
open PCPSPC
/-- Theorem 7, Oper. Res. 68(5), p. 1434: for a destination `d`, a period `t` and a chain of
clusters `c₁ ≺ c₂ ≺ ⋯ ≺ c_n` with `q(rcl(c₁) \ rcl(c_n)) < U_t^d < q(rcl(c₁))`, and constants
`0 ≤ α_b ≤ 1` (`b ∈ c_n`), the VRHS inequality (32) is valid for the PCPSP-F; if moreover (33)
`∑_{b ∈ c_n} α_b q_b ≤ U_t^d − q(rcl(c₁) \ rcl(c_n))` holds, (32) is valid for the PCPSP-P.
Validity is over feasible points that also satisfy the destination capacity rows (9). -/
theorem theorem_7 {B D C : Type} [Fintype B] [Fintype D] [Fintype C] [DecidableEq C] {T m : ℕ}
(I : PCPSPC B D C T m) (hI : I.Standing) (d : D) (t : Fin T) (n : ℕ) (hn : 1 ≤ n)
(c : ℕ → C)
(h1 : ∀ k ∈ Finset.Ico 1 n, I.cprec (c k) (c (k + 1)))
(h2 : I.qSet (I.rcl (c 1) \ I.rcl (c n)) < I.Ud d t)
(h3 : I.Ud d t < I.qSet (I.rcl (c 1)))
(α : B → ℝ) (hα : ∀ b ∈ I.blocksOf {c n}, 0 ≤ α b ∧ α b ≤ 1) :
(∀ (x : C → Fin T → ℝ) (y : B → D → Fin T → ℝ), I.Feasible .F x y → I.DestCap y →
I.vrhsLHS d t c n α y ≤ I.vrhsRHS d t c n x) ∧
(∑ b ∈ I.blocksOf {c n}, α b * I.q b ≤ I.Ud d t - I.qSet (I.rcl (c 1) \ I.rcl (c n)) →
∀ (x : C → Fin T → ℝ) (y : B → D → Fin T → ℝ), I.Feasible .P x y → I.DestCap y →
I.vrhsLHS d t c n α y ≤ I.vrhsRHS d t c n x) := by sorry
end OpenPitMIP.Vrhs
Confirmed by the mission captain (proposal self-audit).
Confirmed by the moderator at approval.