The Hlawka deficit of a candidate constant on a coordinate triple
DefinitionHlawkaSchatten_DiagonalConstruction_NormalizationhlawkaDeficit packages the Hlawka inequality for the finite coordinate power functional and a candidate constant as a single real number, for vectors indexed by an arbitrary finite type:
using the finite coordinate power functional (DiagonalConstruction.lpNorm), which is a norm for . The definition itself accepts every real .
Equivalently, by a theorem in the same source module, equals times the pair-deficit sum minus the triple deficit for (pairGapSum, tripleGap). So says exactly that the triple deficit for is at most times their pair-deficit sum, and a negative value witnesses a strict failure of that bound for the constant .
This single real-valued packaging is what lets the theorems that accompany it manipulate a hypothetical failure algebraically: for , relabeling — permuting and, if needed, replacing by — so that the total norm is at least as large as each of , which can only decrease a negative deficit; and then, for , rescaling so that , which multiplies the deficit by a positive factor.
import Definitions.Def_HlawkaSchatten_DiagonalConstruction_Basic
import Mathlib.Analysis.InnerProductSpace.Basic
import Mathlib.Analysis.InnerProductSpace.Dual
import Mathlib.Analysis.Normed.Lp.PiLp
import Mathlib.Analysis.SpecialFunctions.Pow.Continuity
import Mathlib.Tactic.Abel
/-
Copyright (c) 2026 Ezzeri Esa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Ezzeri Esa
-/
/-! # Relabeling and normalization of a strict counterexample -/
namespace HlawkaSchatten.DiagonalConstruction
variable {ι : Type*} [Fintype ι]
/-- The target inequality with all terms moved to the nonnegative side. -/
noncomputable def hlawkaDeficit (p K : ℝ) (x y z : ι → ℝ) : ℝ :=
(2 * K - 1) * (lpNorm p x + lpNorm p y + lpNorm p z) + lpNorm p (x + y + z) -
K * (lpNorm p (x + y) + lpNorm p (x + z) + lpNorm p (y + z))
end HlawkaSchatten.DiagonalConstruction
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