(This is the ninth lecture in Stevo Todorcevic’s Forcing class, held in the fall of 2012. You can find the eighth lecture here. Quotes by Stevo are in dark blue; some are deep, some are funny, some are paraphrased so use your judgement. As always I appreciate any type of feedback, including reporting typos, in the comments below.)
- We define the notion of properness.
- Show that the poset -Collapse is proper.
- Justin Moore gives some intuition.
- Explain the Open Colouring Axiom.
- Give a related proper poset.