Positivity varieties through examples

Many natural varieties in Lie theory carry positive structures. I will introduce the idea of a "positive point" of a variety through two main examples: the Grassmannian Gr(k,n) and configuration spaces of flags. I'll give several different perspectives on positivity: convexity, sign variation, matroids, rational normal curves.

I hope this will give you some intuition for positive geometry and convince you that it is a natural and interesting notion.