Kelley–Morse set theory does not prove the class Fodor principle
Kelley–Morse set theory does not prove the class Fodor principle
We show that Kelley–Morse KM set theory does not prove the class Fodor principle, the assertion that every regressive class function $F:S\to {\rm Ord}$ defined on a stationary class $S$ is constant on a stationary subclass. Indeed, for every $\omega \leq