Abstract
We study properties of closure operators of singular cofi-
nality, and introduce several ZFC sufficient and equivalent conditions
for the existence of antichain sequences in posets of singular cofinality.
We also notice that the Proper Forcing Axiom implies the Milner-Sauer
conjecture.
| Original language | American English |
|---|---|
| Pages (from-to) | 185-204 |
| Journal | Contributions to Discrete Mathematics |
| Volume | 2 |
| Issue number | 2 |
| State | Published - 2007 |