(This is the second lecture in Stevo Todorcevic’s Forcing class, held in the fall of 2012. You can find the first lecture here. Quotes by Stevo are in dark blue; some are deep, some are funny, some are paraphrased so use your judgement.)
(Also, there are bound to be typos. I would appreciate anyone who could point them out in the comments and I will promptly fix them.)
- Give the classic example of a -centred poset. (The one that adds a “small” subset of .)
- Define the various “Martin numbers”: and .
- Define some small cardinals and .
- Show that and .