Fodor’s lemma

If κ is a regularPlanetmathPlanetmath, uncountable cardinal, S is a stationary subset of κ, and f:κκ is regressive on S (that is, f(α)<α for any αS) then there is some γ and some stationary S0S such that f(α)=γ for any αS0.

Title Fodor’s lemma
Canonical name FodorsLemma
Date of creation 2013-03-22 12:53:14
Last modified on 2013-03-22 12:53:14
Owner Henry (455)
Last modified by Henry (455)
Numerical id 4
Author Henry (455)
Entry type Theorem
Classification msc 03E10
Synonym pushing down lemma
Related topic Stationary
Defines Fodor’s lemma