Fodor's lemma
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In mathematics, particularly in set theory, Fodor's lemma (or the pressing-down lemma) states: Template:Math theorem
In modern parlance, the nonstationary ideal is normal. The lemma was first proved by the Hungarian set theorist, Géza Fodor in 1956.
Template:Math proofThere is a Fodor's lemma for trees:Template:Math theorem Fodor's lemma also holds for Thomas Jech's notion of stationary sets as well as for the general notion of stationary set.
References
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- Preliminary version of an unpublished book: Template:Cite web
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