Add Erdős Problem 595 (K₄-free graph not union of triangle-free, $250 prize)#3775
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henrykmichalewski wants to merge 2 commits intogoogle-deepmind:mainfrom
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Add Erdős Problem 595 (K₄-free graph not union of triangle-free, $250 prize)#3775henrykmichalewski wants to merge 2 commits intogoogle-deepmind:mainfrom
henrykmichalewski wants to merge 2 commits intogoogle-deepmind:mainfrom
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…e-free ($250 prize) Adds formalization of Erdős Problem 595 (Erdős-Hajnal, $250 prize). Reference: https://www.erdosproblems.com/595 Asks whether there exists a K₄-free graph of chromatic number ℵ₁ which cannot be written as a countable union of triangle-free subgraphs. Includes IsCountableUnionOfTriangleFree definition, Folkman/Nešetřil-Rödl finite version, 4 proved lemmas, and edge-colouring reformulation. Assisted by Claude (Anthropic).
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Closes #814 |
mo271
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Apr 17, 2026
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Thanks! Looks good to me and mathemtically correct, just some small suggestions...
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| Copyright 2025 The Formal Conjectures Authors. | |
| Copyright 2026 The Formal Conjectures Authors. |
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CLA bot is not happy -- should be fixed by rewriting history, removing authors that have not signed the CLA by amending the commit(s)... |
…e_colouring - Update copyright year to 2026 - Remove duplicate docstring on IsCountableUnionOfTriangleFree def - Update reformulation_edge_colouring docstring to reference c : G.edgeSet → ℕ - Change attribute to @[category test, AMS 5] - Prove reformulation_edge_colouring using EdgeLabeling.iSup_labelGraph and Sym2.ind Assisted by Claude (Anthropic).
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fixes #814
Problem
Erdős Problem 595: https://www.erdosproblems.com/595 ($250 prize)
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erdos_595Assisted by Claude (Anthropic).