All open problems
Source labels openChecked July 26, 2026

Green's Open ProblemsMeasure and integration

Ben Green's Open Problem 94

Let A ⊂ R be a set of positive measure. Does AA contain an affine copy of {1, 1/2, 1/4, . . . }?

Mathematical statement

Let A ⊂ R be a set of positive measure. Does AA contain an affine copy of {1, 1/2, 1/4, . . . }?

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_94

Canonical source
Complete statement target, proof intentionally absentLean 4
theorem green_94 :   answer(sorry)   A : Set ,   MeasurableSet A  volume A > 0     a b : , a  0   n : , a * (1 / 2^n) + b  A := 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