All open problems
Source labels openChecked July 26, 2026

Green's Open ProblemsCombinatorics

Green's Open Problem 51

Suppose that AF2nA \subset \mathbb{F}_2^n is a set of density α\alpha. What is the largest size of coset guaranteed to be contained in 2A2A?

Mathematical statement

Suppose that AF2nA \subset \mathbb{F}_2^n is a set of density α\alpha. What is the largest size of coset guaranteed to be contained in 2A2A?

We phrase this by asking for the exact function F(α,n)F(\alpha, n) giving the maximum dimension of a guaranteed coset.

Statement source: Green's Open Problems statement material

Statement terms: Source-specific

Source-specific terms. Therefore does not assert reuse rights beyond attributed display.

Statement artifacts, not proofs

These records expose exact Lean propositions and statement-only wrappers. Defining a proposition does not supply a proof of it. A placeholder-bearing target also contains no proof. Elaboration checks syntax and types; it does not certify that a formalization perfectly captures every nuance of the informal problem.

Pinned Lean formulation 1

green_51

Canonical source
Complete statement target, proof intentionally absentLean 4
theorem green_51 : answer(sorry) = guaranteedMaxCosetDim := by  sorry
Statement source
Formal Conjectures
Lean version
v4.27.0
Placeholder
Present; no proof artifact
Source evidence
Pinned source index
Fidelity review
Community formulation

References