Filtration form of Fodor lemma
= Filtration form of Fodor lemma
If $S\subseteq\kappa$ is stationary and $f(\alpha)\in A_\alpha$ for a <kappa-filtration>, then $f$ is constant on a stationary <subset>. Restrict to limit indices and use continuity to find a smaller stage containing each value. <Fodor lemma> fixes that stage on a stationary <subset>. Its size is less than $\kappa$, so <club filter completeness> makes one value fiber stationary.