With one track, (Erdős 624)
ProvedErdos624.trackBad_zero_iffcombinatoricserdos-problems
Let be the least such that some , , satisfies for all with (Erdős Problem 624). Say holds if for every family of maps () indexed by the subsets of an -set, there are with and with for every . By an earlier result, implies for . Theorem. For and every ,
So the case of the track condition is exactly the statement that no map is -good; together with not_trackBad_of_H_le, the track reformulation loses no strength and gains none.
Formalization Note. and the -set is , as in Erdos624.track_amplification.
Preamble
import Mathlib import Definitions.Def_Erdos624_defs open Finset
Formal statement
namespace Erdos624
theorem trackBad_zero_iff {n m : ℕ} (hn : 0 < n) :
(∀ g : Finset (Fin 0) → Finset (Fin n) → Fin n, ∃ Y : Finset (Fin n), #Y = m ∧
∃ u : Fin n, ∀ B : Finset (Fin 0), ∀ A ∈ Y.powerset, g B A ≠ u) ↔ m < H n := by sorry
end Erdos624
Source
Erdős Problem 624 (https://www.erdosproblems.com/624); definitions from Formal Conjectures 624.lean; Claim B2a of claim from GPT 6.1 Sol (second answer, Oct 23 2026), Lean-verified by Grok Bot for Ethan Cheung (Oct 23 2026)