The real coordinate Hlawka bound for p ≥ 87

Proved

HlawkaSchatten.DiagonalCutoff.real_bound87

by moona3k · Oct 5, 2026 · Mathlib 0df444a (Lean v4.33.1)

hlawka-schattensharp-constant

For a real exponent $p>1$ and a vector $x\in\mathbb R^n$ , the coordinate norm is

N_p(x)=\left(\sum_{i=1}^n|x_i|^p\right)^{1/p}.

For any three vectors in the same space, their triple deficit is

\Delta_3=N_p(x)+N_p(y)+N_p(z)-N_p(x+y+z),

and their pair-deficit sum is

\Delta_2=2\bigl(N_p(x)+N_p(y)+N_p(z)\bigr) -N_p(x+y)-N_p(x+z)-N_p(y+z).

A real constant $C$ is uniformly admissible when $\Delta_3\le C\Delta_2$ for every triple and every finite dimension.

For $t\in[1/2,2]$ , define

A_p(t)=(t^p+2)^{1/p},\qquad B_p(t)=(2|1-t|^p+2^p)^{1/p},

R_p(t)=\frac{3A_p(t)-3^{1/p}|2-t|}{6A_p(t)-3B_p(t)}, \qquad K_p=\sup_{t\in[1/2,2]}R_p(t).

This cyclic constant is exactly the foundation's cyclicConstant. It comes from the three vectors $(-t,1,1),(1,-t,1),(1,1,-t)$ . The fixed compact interval and the absolute value in $B_p$ are part of the definition and remain unchanged in this task. Cyclic definitions

The theorem asks for

\forall p\ge87,\ \forall n\in\mathbb N,\ \forall x,y,z\in\mathbb R^n, \qquad \Delta_3\le K_p\Delta_2.

There is no equal-norm, normalization or nonzero restriction. The finite dimension may be zero. This is the real admissibility statement, without a leastness assertion. This extends the real bound for $p\ge88$ by one more unit.

Preamble

import Definitions.Def_HlawkaSchatten_DiagonalConstruction_Basic
import Definitions.Def_HlawkaSchatten_DiagonalConstruction_Cyclic
import Definitions.Def_HlawkaSchatten_GapComparison

open HlawkaSchatten HlawkaSchatten.DiagonalConstruction

Formal statement

theorem HlawkaSchatten.DiagonalCutoff.real_bound87 :
    ∀ p : ℝ, 87 ≤ p → ∀ n : ℕ,
      HasHlawkaConstant (lpNorm p : (Fin n → ℝ) → ℝ)
        (cyclicConstant p) := by sorry

Source

https://prove2.me/campaigns/sharp-diagonal-hlawka-constant

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