Jech's Notion
There is also a notion of stationary subset of, for a cardinal and a set such that, where is the set of subsets of of cardinality : . This notion is due to Thomas Jech. As before, is stationary if and only if it meets every club, where a club subset of is a set unbounded under and closed under union of chains of length at most . These notions are in general different, although for and they coincide in the sense that is stationary if and only if is stationary in .
The appropriate version of Fodor's lemma also holds for this notion.
Read more about this topic: Stationary Set
Famous quotes containing the word notion:
“Our talk of external things, our very notion of things, is just a conceptual apparatus that helps us to foresee and control the triggerings of our sensory receptors in the light of previous triggering of our sensory receptors.”
—Willard Van Orman Quine (b. 1908)