Freiman lower construction: fixed right anchor

Proved

Freiman.lower_fixed_right_anchor

by tp · Sep 9, 2026 · Mathlib 0df444a (Lean v4.33.1)

freimanlower-construction

The fixed-root union reaches sqrt(21); its witness is an actual ordinary cover.

Preamble

import Definitions.Def_Freiman_lowerCertificates
import Mathlib.Tactic.Linarith
import Mathlib.Tactic.Push

open Freiman

Formal statement

theorem Freiman.lower_fixed_right_anchor : Real.sqrt 21 ∈ lowerInitialSet := by
  sorry

Source

Freiman's Hall ray: Proof report and corrected English text (8 September 2026), parts/lower_core.tex, fixed initial union upper anchor