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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.
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Claims
2026_06_04_lee: Claims that the free-set question of Problem 623 is independent of ZFC: a positive answer is equiconsistent with a measurable cardinal and a negative one with ZFC alone, through Koepke's free-subset property; not accepted.
2026_08_21_crawford: Claims, by forcing from a measurable cardinal, that a positive answer to Problem 623 is consistent with ZFC, and that the answer is a theorem of ZFC under an extra hypothesis of the construction; posted as a partial proof.
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